Awesome WPO - Web Performance Optimization

Agent Skills

accessibility

WCAG compliance, screen reader support, and keyboard navigation.

Image Optimizers

AdvPNG

Recompress PNG files to get the smallest possible size.

Real User Monitoring

Akamai mPulse Boomerang

Documentation for the Akamai mPulse version of Boomerang, which includes additions specific to interacting with mPulse.

CDN

Amazon CloudFront

A content delivery network by Amazon that integrates nicely with other Amazon services or can be used standalone.

Web server Benchmarks

Apache JMeter

Open source load testing tool: It is a Java platform application.

Generators

Assetgraph-sprite

Assetgraph transform for auto-generating sprites based on the CSS dependency graph.

Real User Monitoring

Atatus

Full-stack observability including RUM, APM, synthetic uptime, session replay, and OpenTelemetry.

Generators

AtBuild

JavaScript code generation tool that lets you write JavaScript that outputs JavaScript. Good for unrolling loops and writing libraries that compile away the runtime.

Web server Benchmarks

Autoperf

Ruby driver for httperf to automate load and performance testing for a single endpoint or via log replay.

Web server Benchmarks

beeswithmachineguns

A utility for arming (creating) many bees (micro EC2 instances) to attack (load test) targets (web applications).

Metrics Monitor

Bench

Using Phantomas (a PhantomJS-backed client performance metrics scrapper). Benchmark a page, store results in MongoDB, and display results via the built-in server.

Benchmarks

Benchmark.js

A robust benchmarking library that works on nearly all JavaScript platforms, supports high-resolution timers, and returns statistically significant results.

Documentation

Best Practices for Speeding Up Your site

The list includes 35 best practices divided into 7 categories, created by Yahoo! Exceptional Performance team.

Agent Skills

best-practices

Security, modern APIs, and code quality patterns.

Application Performance Monitoring

BetterUptime

A good website monitoring tool (bundling status page, incident notification).

Books

Book of Speed

Stoyan Stefanov.

Real User Monitoring

Boomerang (Open Source)

Documentation for the Open Source version of Boomerang, which is maintained by Akamai employees with contributions from the OSS community.

Extensions

Browser Calories

The easiest way to measure your performance budget.

Metrics Monitor

BrowserView Monitoring

Continually checks web page load times in Internet Explorer, Chrome and Firefox from multiple points around the world.

Bundle Analyzer

Bundlephobia

Helps you find the performance impact of adding an npm package to your frontend bundle.

Bundle Analyzer

Bundlesize

Keep your bundle size in check.

Bundle Analyzer

BundleStats

Generate bundle report(bundle size, assets, modules, packages) and compare the results between different builds.

Real User Monitoring

Catchpoint Real User Monitoring

RUM for web and native mobile apps with Core Web Vitals, third-party impact, and correlation with synthetic monitoring (OpenTelemetry-based).

CDN

CDNjs

An open-source CDN for JavaScript and CSS sponsored by Cloudflare that hosts everything from jQuery and Modernizr to Bootstrap.

CDN

CDNperf

Finds you fast and reliable JavaScript CDNs that make your sites snappy and happy.

Documentation

Chrome Developers: Performance

Deep guides on rendering, loading, and runtime performance.

Documentation

Chrome User Experience Report (CrUX)

Origin-level real-user performance data from Chrome users.

Minifiers

Clean-css

A fast, efficient, and well-tested CSS minifier for node.js.

CDN

Cloudflare CDN

A content delivery network that uses next-gen tech to deliver fast, reliable, CDN services.

Bundle Analyzer

Compression Webpack plugin

Prepare compressed versions of assets to serve them with Content-Encoding.

Image Optimizers

Compressor

Online image compressor for JPG, PNG, SVG and GIF.

Tools

Core Web Vitals Report

Generate a Core Web Vitals report using CrUX historical data.

Agent Skills

core-web-vitals

LCP, INP, and CLS specific optimizations.

Miscellaneous

Critical

Extract & Inline Critical-path CSS in HTML pages (alpha).

Tools

Critical CSS Generator

Generate critical-path CSS for above-the-fold rendering.

Generators

CSS Sprite Generator

CSS sprites allow you to combine multiple images into a single file.

Bookmarklets

CSS Stress

Stress testing and performance profiling for CSS.

Documentation

CSS will-change

This specification defines the `will-change` CSS property which allows an author to declare ahead-of-time what properties are likely to change in the future, so the UA can set up the appropriate optimizations some time before they’re needed. This way, when the actual change happens, the page updates in a snappy manner.

Benchmarks

CSS-perf

Completely unscientific way of testing CSS performance. Most of these tests will revolve around methodologies and techniques for determining effective CSS architecture. Put another way, I want to know what works best given a particular comparison of CSS strategies.

Miscellaneous

Csscolormin

Utility that minifies CSS colors, example: min("white"); // minifies to "#fff".

Minifiers

CSSO

CSS minimizer unlike others. In addition to usual minification techniques, it can perform structural optimization of CSS files, resulting in smaller file size compared to other minifiers.

Minifiers

CSSshrink

Because CSS is ospon the critical path to rendering pages. It must be small! Or else!

Analyzers

Dareboost

[Multi-audit] Website quality testing across performance, accessibility, SEO, and security best practices.

Metrics Monitor

DareBoost

Real Browser Monitoring. Offers complete reports about web performance and quality using YSlow, Page Speed and numerous custom tips.

Application Performance Monitoring

Datadog APM

End-to-end distributed tracing and APM at scale, correlated to all telemetry.

Real User Monitoring

Datadog Real User Monitoring

Browser and mobile RUM with session replay, Core Web Vitals, and correlation with traces and logs.

Analyzers

DebugBear

Site monitoring based on Lighthouse. See how your scores and metrics changed over time, with a focus on understanding what caused each change. Paid product with a free 30-day trial.

Loaders

Defer.js

Async Everything: Make the meat of your pages load faster with this JS morsel.

Books

Designing for Performance: Weighing Aesthetics and Speed

Lara Hogan.

Bundle Analyzer

Disc

Visualise the module tree of browserify project bundles and track down bloat.

Minifiers

Django-compressor

Compresses linked and inline JavaScript or CSS into a single cached file.

Minifiers

Django-htmlmin

HTML minifier for Python with full support for HTML 5. Supports Django, Flask, and any other Python web framework, plus a command-line tool for static sites or deployment scripts.

Minifiers

Django-pipeline

Pipeline is an asset packaging library for Django, providing both CSS and JavaScript concatenation and compression, built-in JavaScript template support, and optional data-URI image and font embedding.

Bookmarklets

DOM Monster

A cross-platform, cross-browser bookmarklet that will analyze the DOM & other features of the page you're on, and give you its bill of health.

Metrics Monitor

Dotcom-tools

Analyze your website's speed in real browsers from 20 locations worldwide.

Books

Even Faster Web Sites: Performance Best Practices for Web Developers

Steve Souders.

Image Optimizers

ExifCleaner

GUI app to remove EXIF metadata from images and video files with drag and drop. Free and open source.

Miscellaneous

Fontaine

Automatic font fallback based on font metrics to reduce Cumulative Layout Shift (CLS) caused by web font loading.

Generators

Glue

A simple command-line tool to generate CSS sprites.

Image Optimizers

Gm

GraphicsMagick and ImageMagick for Node.js.

Web server Benchmarks

Gohttperf

Go Port of HTTPerf.rb.

Documentation

Google Developers Case Studies

Learn why and how other developers have used the web to create amazing web experiences for their users.

CDN

Google Hosted Libraries

Google-run CDN for the most popular open-source JavaScript libraries.

Minifiers

Grunt-contrib-concat

A Grunt plugin to concatenate files.

Minifiers

Grunt-contrib-cssmin

CSS Minifier for Grunt.

Minifiers

Grunt-contrib-htmlmin

A grunt plugin to minify HTML that uses HTMLMinifier.

Image Optimizers

Grunt-contrib-imagemin

Minify PNG and JPEG images for Grunt.

Minifiers

Grunt-contrib-uglify

A Grunt plugin to concatenate and minify JavaScript files.

Minifiers

Grunt-cssshrink

This is just a grunt wrapper for CSS Shrink.

Minifiers

Grunt-htmlcompressor

Grunt plugin for HTML compression, using htmlcompressor.

Image Optimizers

Grunt-imageoptim

Make ImageOptim, ImageAlpha, and JPEGmini part of your automated build process.

Analyzers

Grunt-perfbudget

A Grunt.js task for enforcing a performance budget ([more on performance budgets](https://timkadlec.com/2013/01/setting-a-performance-budget/)).

Metrics Monitor

Grunt-phantomas

Grunt plugin wrapping phantomas to measure frontend performance.

Image Optimizers

Grunt-smushit

Grunt plugin to remove unnecessary bytes of PNG and JPG using Yahoo Smushit.

Generators

Grunt-sprite-css-replace

Grunt task that generates a sprite from images referenced in a style sheet and then updates the references with the new sprite image and positions.

Generators

Grunt-spritesmith

Grunt task for converting a set of images into a sprite sheet and corresponding CSS variables.

Generators

Grunt-svg-sprite

SVG sprites & stacks galore — Grunt plugin wrapping around svg-sprite that reads in a bunch of SVG files, optimizes them and creates SVG sprites and CSS resources in various flavors.

SVG

Grunt-svgmin

Minify SVG using SVGO for Grunt.

Minifiers

Grunt-uncss

A grunt task for removing unused CSS from your projects.

Image Optimizers

Grunt-WebP

Convert your images to WebP format.

Analyzers

Grunt-WebPageTest

Grunt plugin for continuous measurement of WebPageTest. ([Demo](http://sideroad.github.io/sample-wpt-page/))

Metrics Monitor

GTmetrix

Free tool to test and monitor your page's performance. Uses Lighthouse to score your pages and offers actionable recommendations on how to optimize them.

Loaders

Guess.js

Predictive prefetching and performance optimization using analytics and machine learning.

Minifiers

Gulp-cssshrink

Shrinks CSS files using cssshrink for Gulp.

CDN

Gulp-google-cdn

Replaces script references with Google CDN ones.

Minifiers

Gulp-htmlmin

A gulp plugin to minify HTML that uses HTMLMinifier.

Image Optimizers

Gulp-imagemin

Minify PNG, JPEG, GIF and SVG images with imagemin for Gulp.

Image Optimizers

Gulp-smushit

Gulp plugin to optimize PNG and JPG using Yahoo Smushit. Made on top of smosh.

Generators

Gulp-sprite

Gulp task for creating an image sprite and the corresponding style sheets for Gulp.

Generators

Gulp-svg-sprites

Gulp task for creating SVG sprites.

SVG

Gulp-svgmin

Minify SVG with SVGO for Gulp.

Minifiers

Gulp-uncss

A gulp task for removing unused CSS from your projects.

Web Components

Gulp-vulcanize

Concatenate a set of Web Components into one file that use Vulcanize.

Image Optimizers

Gulp-WebP

Convert images to WebP for Gulp.

Loaders

HeadJS

The only script in your HEAD. for Responsive Design, Feature Detections, and Resource Loading.

Books

High Performance Browser Networking: What every web developer should know about networking and web performance

Ilya Grigorik.

Books

High Performance JavaScript

Nicholas C. Zakas.

Books

High Performance Responsive Design: Building Faster Sites Across Devices

Tom Barker.

Books

High Performance Web Sites: Essential Knowledge for frontend Engineers

Steve Souders.

Minifiers

HTML Minifier Online

A HTML min tool by kangax (HTMLMinifier Creator).

Minifiers

HTML_minifier

Ruby wrapper for kangax html-minifier.

Minifiers

HTML_press

Ruby gem for compressing html, that removes all whitespace junk, and leaves only HTML.

Minifiers

Html-minifier

A simple Windows command-line tool to minify your HTML, Razor views & Web Forms views.

Minifiers

HTMLCompressor

Small, fast Java library that minifies HTML or XML by removing extra whitespace, comments, and unneeded characters without breaking structure. Includes a command-line build.

Minifiers

HTMLMinifier

Highly configurable, well-tested, JavaScript-based HTML minifier with lint-like capabilities.

Documentation

HTTP Archive

It's a permanent repository of web performance information such as size of pages, failed requests, and technologies utilized. This performance information allows us to see trends in how the Web is built and provides a common data set from which to conduct web performance research.

Books

HTTP/2 in Action by Barry Pollard

Barry Pollard.

Web server Benchmarks

HTTPerf

Measures web server performance with flexible generation of HTTP workloads and server metrics.

Web server Benchmarks

HTTPerf.js

JS Port of HTTPerf.rb.

Web server Benchmarks

HTTPerf.py

Python Port of HTTPerf.rb.

Web server Benchmarks

HTTPerf.rb

Simple Ruby interface for httperf, written in Ruby.

Miscellaneous

HTTPinvoke

A no-dependencies HTTP client library for browsers and Node.js with a promise-based or Node.js-style callback-based API to progress events, text, and binary file upload and download, partial response body, request and response headers, status code.

Other Awesome Lists

iamakulov/awesome-webpack-perf

A curated list of Webpack tools for web performance.

Books

Image Optimization

Addy Osmani.

Image Optimizers

ImageEngine

Cloud service for optimizing, resizing and caching images on the fly with great mobile support.

Image Optimizers

ImageKit.io

Intelligent real-time image optimizations, image transformations with a global delivery network and storage.

Image Optimizers

Imagemin

Minify images seamlessly with Node.js.

Image Optimizers

Imageoptim

Free app that makes images take up less disk space and load faster, without sacrificing quality. It optimizes compression parameters, and removes junk metadata and unnecessary color profiles.

Image Optimizers

ImageOptim-CLI

Automates ImageOptim, ImageAlpha, and JPEGmini for Mac to make batch optimization of images part of your automated build process.

Image Optimizers

Imager

Automated image compression for efficiently distributing images on the web.

Other Awesome Lists

imteekay/web-performance-research

Research in Web Performance.

Loaders

InstantClick

Preloads pages on hover so in-site links feel instant.

Loaders

JIT

A JIT (Just In Time) plugin loader for Grunt. The load time of Grunt does not slow down even if there are many plugins.

Image Optimizers

Jpegoptim

Utility to optimize/compress JPEG files.

CDN

jQuery

Official CDN for the latest stable releases, powered by MaxCDN.

Benchmarks

JSBench

A modern browser-based JavaScript benchmarking tool for quickly creating and sharing performance tests.

Minifiers

JSCompress

The most minimalistic online JS Compress tool.

CDN

jsDelivr

Similar to Google Hosted Libraries, jsDelivr is an open-source CDN that allows developers to host their own projects and anyone to link to our hosted files on their sites.

Minifiers

JShrink

PHP class that minifies JavaScript for faster delivery to the client.

Benchmarks

JSlitmus

Lightweight tool for creating ad-hoc JavaScript benchmark tests.

Benchmarks

JSPerf

Create and share test cases comparing JavaScript snippet performance via benchmarks. `Follow this issue for updates: https://github.com/jsperf/jsperf.com/issues/537`.

Web server Benchmarks

k6

An open-source load testing tool built for developers. Easy to integrate into CI pipelines. Tests are written in ES6 JS and you can test APIs, microservices and sites using HTTP/1.1, HTTP/2 and WebSocket.

Metrics Monitor

Keepfast

Tool to monitor indicators related to the performance of a web page.

Minifiers

Koa HTML Minifier

Middleware that minifies your HTML responses using html-minifier. It uses html-minifier's default options which are all turned off by default, so you have to set the options otherwise it's not going to do anything.

Image Optimizers

Kraken Web-interface

Optimize your images and will be available for download for 12 hours.

Loaders

Labjs

An open-source (MIT license) project supported by Getify Solutions. The core purpose of LABjs is to be an all-purpose, on-demand JavaScript loader, capable of loading any JavaScript resource, from any location, into any page, at any time.

Documentation

Largest Contentful Paint API (MDN)

Programmatic access to LCP entries.

Bundle Analyzer

Lasso-analyzer

Analyze and visualise project bundles created by Lasso.

Documentation

Layout Instability API (MDN)

Measure and inspect layout shifts (CLS).

Lazyloaders

lazyload

Defer images, iframes, and widgets with a standalone JavaScript lazyloader (~1kb).

Miscellaneous

Lazysizes

High-performance lazy loader for images (responsive and normal), iframes, and scripts, that detects any visibility changes triggered through user interaction, CSS or JavaScript without configuration.

Books

Lean sites

Barbara Bermes.

Image Optimizers

Leanify

Lightweight lossless file minifier/optimizer.

Analyzers

Lightest App

Webpage load time is extremely important for conversion and revenue. Visualize web performance against competitors.

Core Web Vitals

Lighthouse

Audits Core Web Vitals in lab conditions (see [Analyzers](#analyzers)).

Core Web Vitals

Lighthouse CI

Run Lighthouse in CI to enforce Core Web Vitals budgets on every commit.

Documentation

Lighthouse Docs

Audit methodology, scoring details, and usage guidance.

Books

Linux, Apache, MySQL, PHP Performance end-to-end

Colin McKinnon.

Web server Benchmarks

Locust

An open-source load testing tool. Define user behaviour with Python code, and swarm your system with millions of simultaneous users.

Documentation

Long Tasks API (MDN)

Detect main-thread blocking work.

Lazyloaders

lozad.js

Highly performant, light ~0.9kb, and configurable lazy loader in pure JS with no dependencies for responsive images, iframes, and more.

Benchmarks

Matcha

Lets you design experiments that measure the performance of your code. Each bench should focus on a specific point of impact in your application.

Benchmarks

Memory-stats.js

Minimal monitor for JS Heap Size via performance memory.

Minifiers

Minimize

HTML minifier based on node-htmlparser; currently server-side only. Client-side minification is planned.

Image Optimizers

mozjpeg

Improved JPEG encoder.

Documentation

Navigation Timing

This specification defines a unified interface to store and retrieve high resolution performance metric data related to the navigation of a document.

Documentation

Navigation Timing API (MDN)

Page navigation and load milestone metrics.

Documentation

Navigation Timing Level 2 (W3C)

Use `responseStart` and `requestStart` to derive Time to First Byte (TTFB).

Real User Monitoring

New Relic Browser Monitoring

Real-user browser monitoring with Core Web Vitals, distributed tracing to backend, and deployment markers.

Image Optimizers

Optimizt

CLI image optimization tool. It can compress PNG, JPEG, GIF and SVG lossy and lossless, and also create AVIF and WebP versions for raster images.

Image Optimizers

OptiPNG

PNG optimizer that recompresses image files to a smaller size without losing information.

Analyzers

Page Speed

The PageSpeed family of tools is designed to help you optimize the performance of your site. PageSpeed Insights products will help you identify performance best practices that can be applied to your site, and PageSpeed optimization tools can help you automate the process.

Documentation

Page Visibility

This specification defines a means for site developers to programmatically determine the current visibility state of the page in order to develop power and CPU-efficient web applications.

CDN

PageCDN

A state-of-the-art opensource CDN with aggressive content optimization using brotli-11 compression, HTTP/2 server push, better HTTP/2 multiplexing, and more. Supports 100s of libraries and 2000+ WordPress themes already. Easy to use, easy to link, and very fast.

Analyzers

PageGym

Advanced page speed analysis and optimization tool for experienced users and technical SEO professionals.

Analyzers

Pagelocity

A web performance optimization and analysis tool.

Analyzers

PageSpeed Insights

Lab and field CWV diagnostics for any URL.

Documentation

PageSpeed Insights Rules

A guide created by PageSpeed Team.

Web server Modules

PageSpeed Module

PageSpeed speeds up your site and reduces page load time. This open-source web server module automatically applies web performance best practices to pages and associated assets (CSS, JavaScript, images) without requiring that you modify your existing content or workflow. PageSpeed is available as a module for Apache 2.x and Nginx 1.x.

Documentation

Paint Timing API (MDN)

First paint and first contentful paint signals.

Metrics Monitor

Perfjankie

Runtime Browser Performance regression suite ([Demo](https://github.com/asciidisco/perfjankie-test)).

Bookmarklets

PerfMap

A bookmarklet to create a frontend performance heatmap of resources loaded in the browser using the Resource Timing API.

Conferences

PerfMatters

Conference is the ONLINE web performance conference by internationally renowned performance developers.

Agent Skills

performance

Loading speed, runtime efficiency, and resource optimization.

Books

Performance Engineering in Practice

Den Odell.

Documentation

Performance Timeline

This specification defines a unified interface to store and retrieve performance metric data. This specification does not cover individual performance metric interfaces.

Bookmarklets

Performance-Bookmarklet

Analyze the current page through the Resource Timing API, Navigation Timing API and User-Timing - Sort of a light live WebPageTest. As [Firefox Add-on](https://addons.mozilla.org/en-US/firefox/addon/performance-analyser/?src=cb-dl-created) under the name Performance-Analyser.

Conferences

performance.now()

The performance.now() conference will return to Amsterdam! We're a single-track conference with fourteen world-class speakers, covering today’s most important web performance insights.

Benchmarks

PerfTests

Performance tests of JavaScript inheritance models.

Metrics Monitor

Perfume.js

Tiny library to collect Core Web Vitals and other performance metrics from real users.

Metrics Monitor

Phantomas

PhantomJS-based web performance metrics collector and monitoring tool.

Benchmarks

php-bench

Benchmark and profile PHP code blocks whilst measuring the performance footprint.

Web server Benchmarks

PHP-httperf

PHP Port of HTTPerf.rb.

Benchmarks

PHPench

Graphical output for PHP benchmarks: plot any function's runtime in real time with GnuPlot and export an image of the result.

Metrics Monitor

Pingbreak.com

Free site and SSL Monitoring with response time alerting (on Slack, Twitter, Mattermost, Discord or custom Webhook).

Application Performance Monitoring

Pingdom

A tool to get the uptime of your website (with probes from different locations).

Metrics Monitor

Pingdom site Speed Test

Test the load time of that page, analyze it, and find bottlenecks.

Generators

Pitomba-spriter

Spriter is a simple and flexible dynamic sprite generator for CSS, using Python. It can process CSS both synchronous and asynchronous as it provides classes to be used in your Python code and also a watcher that listens to your filesystem and changes CSS and sprite as soon as a static is changed.

Web Components

Polymer Bundler

Polymer-bundler is a library for packaging project assets for production to minimize network round-trips.

Loaders

prerender.js

Preloads pages and assets ahead of navigation for faster page transitions.

Minifiers

Prettyugly

Uglify (strip spaces) or prettify (add consistent spaces) CSS code.

Analyzers - API

PSI

PageSpeed Insights for Node.js - with reporting.

Metrics Monitor

puppeteer-webperf

Collect web performance metrics in Puppeteer scripts.

Conferences

PWA Summit

A free, online, single-track conference focused on helping everyone succeed with Progressive Web Apps.

Lazyloaders

quicklink

Prefetch links in the viewport (via Intersection Observer) to make future navigations faster.

Analyzers

Redirect Checker

Analyze HTTP redirect chains, detect loops, and measure performance impact on page load times.

Analyzers

Request Map

Visualize first- and third-party request dependencies as an interactive map.

Loaders

RequireJS

JavaScript file and module loader. It is optimized for in-browser use, but it can be used in other JavaScript environments, like Rhino and Node.js.

Documentation

Resource Hints

This specification defines the dns-prefetch, preconnect, prefetch, and prerender relationships of the HTML Link Element (<link>). These primitives enable the developer, and the server generating or delivering the resources, to assist the user agent in the decision process of which origins it should connect to, and which resources it should fetch and preprocess to improve page performance.

Documentation

Resource Timing

This specification defines an interface for web applications to access the complete timing information for resources in a document.

Documentation

Resource Timing API (MDN)

Detailed network timing for assets.

Image Optimizers

ResponsiveImage

Generate optimized images (WebP, AVIF) and LQIP placeholders using Vite or Webpack plugins and render responsive image markup with an image component for multiple frameworks.

Documentation

RFC 9218: HTTP Prioritization

Protocol-level prioritization mechanisms for HTTP.

SVG

Scour

Open-source Python script that aggressively cleans SVG files, stripping cruft that tools or authors embed in documents.

Analyzers

Screpy

[Multi-audit] AI-based performance, SEO, uptime, and quality monitoring.

Image Optimizers

Sharp

The typical use case for this high-speed Node.js module is to convert large images of many formats to smaller, web-friendly JPEG, PNG, and WebP images of varying dimensions.

Image Optimizers

Shortpixel

Compress Your Image by removing unnecessary bytes of the image and Convert it into WebP/AVIF.

Metrics Monitor

Sitespeed.io

Open-source tool that checks your site against web performance best practices and uses the Navigation Timing API to collect metrics. Outputs XML and HTML reports.

Image Optimizers

Smush it

Uses format-specific optimization to remove unnecessary bytes from image files. Lossless: optimizes images without changing their look or visual quality.

Miscellaneous

Socialite.js

Socialite provides a very easy way to implement and activate a plethora of social sharing buttons — any time you wish. On document load, on article hover, on any event.

Bundle Analyzer

source-map-explorer

Analyze and debug bundle space usage through source maps.

Tools

Speculation Rules Generator

Build speculation rules JSON for prefetch and prerender configurations.

Analyzers

Speed Racer

Collect performance metrics for your library/application using Chrome headless.

Real User Monitoring

SpeedCurve

Web performance monitoring combining synthetic testing, RUM, Lighthouse, Core Web Vitals, performance budgets, and competitive benchmarking.

Generators

Sprite Cow

Get the background-position, width, and height of sprites within a spritesheet as copyable CSS.

Generators

Sprite Factory

The sprite factory is a ruby library that can be used to generate CSS sprites. It combines individual image files from a directory into a single unified sprite image and creates an appropriate CSS style sheet for use in your web application.

Generators

Sprity

A modular image sprite generator with a lot of features: supports retina sprites, supports different output formats, generates sprites and proper style files out of a directory of images, etc...

Benchmarks

Stats.js

This class provides a simple info box that will help you monitor your code performance.

Application Performance Monitoring

StatusList

Uptime, performance monitoring with debug details, and hosted status page in one simple dashboard.

SVG

SVG Cleaner

Cleans SVG files of unnecessary data with batch mode, many cleanup options, and threaded processing on multicore CPUs.

SVG

SVG OMG

SVGOMG is SVGO's Missing GUI, aiming to expose the majority, if not all the configuration options of SVGO.

SVG

SVGO

Node.js-based optimizer for SVG vector graphics.

Generators

SvgToCSS

Optimizes and renders SVG files in CSS / Sass sprites.

Image Optimizers

Tapnesh-CLI

Tapnesh is a CLI tool that will optimize all your images in parallel easily and efficiently!

Analyzers

Third Party Analysis Tool

Analyze third-party request risk, render-blocking impact, and potential single points of failure from WebPageTest runs.

Books

Time Is Money: The Business Value of Web Performance

Tammy Everts.

Benchmarks

Timing.js

Small helpers for working with the Navigation Timing API to identify where your application is spending its time. Useful as a standalone script, DevTools snippet, or bookmarklet.

Image Optimizers

Tinypng

Advanced lossy compression for PNG images that preserves full alpha transparency.

Miscellaneous

TMI

Too Many Images: discover your image weight on the web.

Image Optimizers

Trimage

A cross-platform tool for losslessly optimizing PNG and JPG files.

Miscellaneous

uCSS

Crawls large sites to find unused CSS selectors (does not remove unused CSS).

Minifiers

UglifyJS2

UglifyJS is a JavaScript parser, minifier, compressor or beautifier toolkit, written in JavaScript.

Application Performance Monitoring

UptimeRobot

Another uptime monitoring tool (with a generous free plan).

Documentation

User Timing

This specification defines an interface to help web developers measure the performance of their applications by giving them access to high-precision timestamps.

Books

Using WebPagetest

Rick Viscomi, Andy Davies, Marcel Duran.

Analyzers

Waterfall Tools

Advanced client-side network request waterfall viewer for HAR, WPT JSON, Chrome traces/netlogs, and tcpdump captures.

Conferences

We Love Speed

Born from the desire to share knowledge and experiences in web performance as widely as possible.

Books

Web Components in Action

Ben Farrell.

Analyzers

Web Font Analyzer

Inspect font loading timing, payload, and glyph usage using WebPageTest data.

Books

Web Performance Daybook Volume 2

Stoyan Stefanov.

Books

Web Performance Engineering in the Age of AI

Addy Osmani.

Books

Web Performance in Action by Jeremy Wagner

Jeremy L. Wagner.

Books

Web Performance Tuning

Patrick Killelea.

Documentation

Web Performance Working Group

The mission of the Web Performance Working Group, part of the Rich Web Client Activity, is to provide methods to measure aspects of application performance of user agent features and APIs.

Analyzers

Web Tracing Framework

Libraries, tools, and visualizers for tracing and investigating complex web applications.

Agent Skills

web-quality-audit

Comprehensive quality review across all categories.

Core Web Vitals

web-vitals

Small library to accurately measure Core Web Vitals (LCP, FID, CLS, INP, TTFB) in the browser.

Analyzers

Web.dev

Get the web's modern capabilities on your own sites and apps with useful guidance and analysis from web.dev.

Analyzers

Webfont Usage Analyzer

Bookmarklet script to map loaded web fonts to visible DOM usage and help spot font optimization opportunities.

Web server Modules

WebP-detect

WebP with Accept negotiation.

Bundle Analyzer

Webpack bundle analyzer

Webpack plugin and CLI utility that represents bundle content as a convenient interactive zoomable treemap.

Metrics Monitor

WebPageTest

Run a free site speed test from multiple locations around the globe using real browsers (IE and Chrome) and at real consumer connection speeds. You can run simple tests or perform advanced testing including multi-step transactions, video capture, content blocking and much more. Your results will provide rich diagnostic information including resource-loading waterfall charts, Page Speed optimization checks and suggestions for improvements.

Metrics Monitor

WebPageTest API Wrapper for Node.js

WebPageTest API Wrapper is an npm package that wraps WebPageTest API for Node.js as a module and a command-line tool.

Metrics Monitor

WebPerformance Report

Web performance report every week in your inbox. Get a Personalized Report on the Status of the E-commerce or Website that you want to monitor in terms of Web performance and Web optimization, Core Web Vitals are included.

Documentation

WPOStats

Case studies and experiments demonstrating the impact of web performance optimization (WPO) on user experience and business metrics.

Web server Benchmarks

wrk

A HTTP benchmarking tool (with optional Lua scripting for request generation, response processing, and custom reporting).

Bookmarklets

Yahoo YSlow for Mobile/Bookmarklet

YSlow analyzes web pages and suggests ways to improve their performance based on a set of rules for high-performance web pages.

Analyzers

Yandex.Tank

An extensible open-source load testing tool for advanced Linux users which is especially good as a part of an automated load testing suite.

Analyzers

Yellow Lab Tools

Online quick and easy tool that audits frontend bad practices, reveals performance issues, and profiles JavaScript.

Books

You Don't Know JS: Async & Performance

Kyle Simpson.

Analyzers

YSlow

Analyzes web pages and suggests ways to improve their performance based on a set of rules for high-performance web pages.

Articles

10 JavaScript Performance Boosting Tips

by Nicholas C. Zakas

Talks

7 Levels of a Web Performance Journey - by NY Web Performance Meetup

Talks

7 Levels of a Web Performance Journey - Sergey Chernyshev - performance.sync() 2025 - by Web Conferences Amsterdam

Talks

A Dao of CSS - John Allsopp - CSS Day 2025 - by Web Conferences Amsterdam

Talks

A developer's guide to rendering performance (2013) - by Paul Lewis

Talks

Ad-Supported Sites Without the Slowdown - by NY Web Performance Meetup

Talks

Aiming for the Stars | Annie Sullivan | performance.now() 2024 - by Web Conferences Amsterdam

Meetups

Barcelona Web Performance Group

Barcelona, Spain 🇪🇸

Talks

Behind the scenes of the worlds highest converting checkout - by NY Web Performance Meetup

Meetups

Berlin Web Performance Group

Berlin, Germany 🇩🇪

Talks

Bloomberg Becomes Browser | Jason Williams & Paul Williams | performance.now() 2024 - by Web Conferences Amsterdam

Meetups

Boston Web Performance Group

Boston, USA 🇺🇸

Talks

Building a Computer with CSS - Amit Sheen - CSS Day 2025 - by Web Conferences Amsterdam

Meetups

Cologne Web Performance Group

Cologne, Germany 🇩🇪

Talks

Compression Dictionaries: Early Findings - Robin Marx - performance.sync() 2025 - by Web Conferences Amsterdam

Articles

Core Web Vitals

by Addy Osmani

Talks

Critical Rendering Path (2014) - by João Lucas P Santana

Talks

CSS Performance Tooling (2014) - by Addy Osmani

Talks

CSS tried to come for my Job - Cyd Stumpel - CSS Day 2025 - by Web Conferences Amsterdam

Talks

Curso WPO - Web Performance Optimization 2013 - by Pablo Martinez

Talks

Custom Performance Metrics - by NY Web Performance Meetup

Talks

Delivering the goods (2014) - by Paul Irish

Talks

Design Token Architecture - Brad and Ian Frost - CSS Day 2025 - by Web Conferences Amsterdam

Talks

Digging into Interaction to Next Paint - by NY Web Performance Meetup

Talks

Discovering the next big performance opportunities - by NY Web Performance Meetup

Talks

display: green; applying the web sustainability guidelines - Hidde de Vries - CSS Day 2025 - by Web Conferences Amsterdam

Talks

Dotdash Meredith's culture of performance monitoring and optimization - by NY Web Performance Meetup

Meetups

Dutch Web Performance & Operations Meetup

Amsterdam, Netherlands 🇳🇱

Articles

Fast

by web.dev

Talks

Flexible Architectures for Web Performance - by NY Web Performance Meetup

Talks

Font Performance - by NY Web Performance Meetup

Articles

Forget Google and Use These Hosted JavaScript Libraries in China

by Ryan

Talks

Form control styling - Tim Nguyen - CSS Day 2025 - by Web Conferences Amsterdam

Talks

Frameworks for humans in the age of machines - by NY Web Performance Meetup

Articles

Getting started with the Picture Element

by Dean Hume

Meetups

Hamburg Web Performance Group

Hamburg, Germany 🇩🇪

Talks

How Dotdash Meredith team approaches INP - by NY Web Performance Meetup

Articles

How to read a WebPageTest Connection View chart

by Matt Hobbs

Articles

How to read a WebPageTest Waterfall View chart

by Matt Hobbs

Articles

How to run a WebPageTest test

by Matt Hobbs

Articles

How to use standard HTML video and audio lazy loading on the web today

by Squarespace Engineering

Articles

Idle Until Urgent

by Philip Walton

Articles

Improve Page Load Times With DNS Prefetching

by Dean Hume

Talks

Improving performance for 3 million sites - by NY Web Performance Meetup

Talks

Improving Web Responsiveness - Andrea Verlicchi - performance.sync 2025 - by Web Conferences Amsterdam

Meetups

Indianapolis Web Performance Group

Carmel, USA 🇺🇸

Talks

INP Case Studies | Erwin Hofman & Karlijn Löwik | performance.now() 2024 - by Web Conferences Amsterdam

Articles

Introducing Waterfall Tools

by Patrick Meenan

Talks

Is Sass Dead Yet? CSS Mixins and Functions - Miriam Suzanne - CSS Day 2025 - by Web Conferences Amsterdam

Articles

Jank busting for better rendering performance

by Tom Wiltzius

Talks

Jank Free: Chrome Rendering Performance (2013) - by Nat Duca and Tom Wiltzius

Articles

JavaScript Memory Profiling

by Google

Meetups

Karlsruhe Web Performance Group

Karlsruhe, Germany 🇩🇪

Talks

Level, Up your Scroll UX - Adam Argyle - CSS Day 2025 - by Web Conferences Amsterdam

Talks

Lies, damn lies, and performance studies - by NY Web Performance Meetup

Articles

Loading webfonts with high performance on responsive sites

by Adam Beres-Deak

Meetups

London Web Performance Group

London, UK 🇬🇧

Articles

Measure Performance in JavaScript

by Prasanna Brabourame

Talks

Measuring Interactions and Navigations - Michal Mocny - performance.now() 2025 - by Web Conferences Amsterdam

Talks

Multicol and fragmentation - Rachel Andrew - CSS Day 2025 - by Web Conferences Amsterdam

Meetups

Munich Web Performance Group

Munich, Germany 🇩🇪

Meetups

New York Web Performance Group

New York City, USA 🇺🇸

Talks

Noise-Cancelling RUM-Based Alerting - Brian Ramirez - performance.sync() 2025 - by Web Conferences Amsterdam

Talks

O melhor da monitoração de Web Performance (2014) - by Davidson Fellipe

Articles

Optimize CLS

by web.dev

Articles

Optimize INP

by web.dev

Articles

Optimize LCP

by web.dev

Talks

Optimizing Ads - by NY Web Performance Meetup

Talks

Peak Performance with Partytown - Julian Jandl - performance.sync() 2025 - by Web Conferences Amsterdam

Articles

Performance As Design

by Brad Frost

Articles

Performance Calendar

Talks

Performance em jQuery apps (2012) - by Davidson Fellipe

Talks

Performance Mistakes-an HTTP Archive deep dive - by NY Web Performance Meetup

Talks

Performance on a Budget: Lessons from Building a Nonprofit SaaS Platform - by NY Web Performance Meetup

Talks

Performance Testing using Playwright - by NY Web Performance Meetup

Talks

Performance Tooling (2013) - by Paul Irish

Talks

Preload v Early Hints v Fetch Priority - by NY Web Performance Meetup

Articles

Preventing 'layout thrashing'

by Wilson Page

Talks

Priority Hints - What Your Browser Doesn’t Know (Yet) - by NY Web Performance Meetup

Talks

Refactoring CSS - Ana Rodrigues - CSS Day 2025 - by Web Conferences Amsterdam

Meetups

San Diego Web Performance Group

San Diego, USA 🇺🇸

Meetups

San Francisco & Silicon Valley Web Performance Group

San Francisco, USA 🇺🇸

Meetups

Santa Cruz Web Performance Meetup

Santa Cruz, USA 🇺🇸

Talks

Scope in CSS - Chris Coyier - CSS Day 2025 - by Web Conferences Amsterdam

Articles

Serving Static Content with Cloud Storage? Don't Forget the CDN!

by Paul Calvano

Talks

Several Components are Rendering A Client Performance at Slack Scale - by NY Web Performance Meetup

Talks

Site Performance Optimization - The Critical Rendering Path - by Udacity

Talks

Smart Layouts - Ahmad Shadeed - CSS Day 2025 - by Web Conferences Amsterdam

Interviews

SPDY STREAM 001 w/ Guest Vinicius Dallacqua

Interviews

SPDY STREAM 002 w/ Dan Gayle of Shopify

Interviews

SPDY STREAM 003 with Akamai's Tim Vereecke and Robin Marx

Interviews

SPDY STREAM 004 with Shawn O'Neill

Interviews

SPDY STREAM 005 with Google's Felix Arntz

Interviews

SPDY STREAM 006 with Cliff Crocker, Karlijn Lowik, Philip Tellis

Interviews

SPDY STREAM 007 with Tammy Everts of SpeedCuvre

Interviews

SPDY STREAM 008 with Todd Gardner

Interviews

SPDY STREAM 009 with Weston Ruter

Interviews

SPDY STREAM 010 with Jacob Gross of Framer

Interviews

SPDY STREAM 011 with with Mateusz Krzeszowiak and Yoav Weiss of Shopify

Interviews

SPDY STREAM 012 with Scott Jehl of SquareSpace

Interviews

SPDY STREAM 013 with Erik Witt of Speed Kit

Interviews

SPDY STREAM 014 with Philip Tellis of Akamai

Interviews

SPDY STREAM 015 with Nic Jansma and Robin Marx of Akamai

Interviews

SPDY STREAM 016 with Amrik Malhans of Yottaa

Interviews

SPDY STREAM 017 with Andrea Verlicchi of Speed Kit by Baqend

Interviews

SPDY STREAM 018 with Matt Zeunert of DebugBear on Effective Monitoring

Interviews

SPDY STREAM 019 with Edwin Molina Hernandez of The Webperformance Report

Interviews

SPDY STREAM 021 with Marcy Sutton-Todd on Accessibility and Performance

Interviews

SPDY STREAM 022 with Arjen Karel. Launching a Fast and Free Personal Page.

Interviews

SPDY STREAM 023 with David Belson of Cloudflare: Cloudflare Radar 2025 Year in Review

Interviews

SPDY STREAM 024 | The JPEG XL with Jon Sneyers of Cloudinary

Interviews

SPDY STREAM 025 with Jodie Chan of Chinafy

Interviews

SPDY STREAM 026 with Caleb Queern of KPMG

Talks

Speculation Rules in a Nutshell - Medhat Dawoud - performance.sync() 2025 - by Web Conferences Amsterdam

Talks

Speculations about Web Performance - Barry Pollard - performance.now() 2025 - by Web Conferences Amsterdam

Talks

Speed Design - by NY Web Performance Meetup

Talks

Styling new HTML UI capabilities - Brecht De Ruyte - CSS Day 2025 - by Web Conferences Amsterdam

Talks

Sub second page load on mobile using intelligent prefetching - by NY Web Performance Meetup

Talks

The Future of Loading on the Web (Chrome Dev Summit 2017) - by Sam Saccone

Talks

The goose and the common - Bruce Lawson - CSS Day 2025 - by Web Conferences Amsterdam

Talks

The Hidden Performance Cost of Web Videos - by NY Web Performance Meetup

Articles

Third Parties and Single Points of Failure

by Paul Calvano

Meetups

Toronto Web Performance Group

Toronto, Canada 🇨🇦

Articles

Total deferring of JavaScript Parsing

by Patrick Sexton

Talks

Unpacking Bundling | Daniel Roe | performance.now() 2024 - by Web Conferences Amsterdam

Talks

Using Model Context Protocol (MCP) - Michael Hablich - performance.sync() 2025 - by Web Conferences Amsterdam

Meetups

Vancouver Web Performance Group

Vancouver, Canada 🇨🇦

Meetups

Vienna Web Performance Group

Vienna, Austria 🇦🇹

Talks

We Love LoAF and INP - by NY Web Performance Meetup

Talks

Web Components Can’t Save Us. (But You Can!) - by NY Web Performance Meetup

Articles

Web Fonts Performance: Making Pretty, Fast

by Ilya Grigorik

Articles

Web Page Performance - Profiling paint times

by Dean Hume

Talks

Web performance made easy (Google I/O '18) - by Ewa Gasperowicz, Addy Osmani

Talks

Web Performance Optimization (2012) - by Pedro Martínez

Articles

WebPageTest comparison URL generator

by Matt Hobbs

Talks

WebPageTest Opportunities and Experiments - by NY Web Performance Meetup