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Free DevOps & SRE Tools
Calculators, checkers, and generators for everyday uptime work. All free, all in your browser.
Calculators
SLA & Uptime Calculator
Convert SLA uptime percentages to allowed downtime per day, week, month, and year — or calculate uptime from observed outages.
Downtime Cost Calculator
Estimate the financial impact of outages based on revenue, team size, and SLA penalties.
Error Budget Calculator
Track your SLO error budget: see how much is left, your burn rate, and when it runs out.
Templates & Generators
Cron Expression Builder
Build cron schedules visually, decode expressions into plain English, and preview upcoming run times.
Incident Communication Template
Generate clear incident updates for your status page or Slack channel. Markdown and plain text output.
Post-Mortem Generator
Create blameless, SRE-style post-mortem documents with timeline, root cause, and action items.
HTTP Status Code Reference
Interactive reference for all HTTP status codes with explanations, common causes, and fixes.
DNS & Email
DNS Lookup
Query A, AAAA, MX, TXT, CNAME, NS, SOA, and CAA records for any domain from your browser.
DNS Propagation Checker
Compare DNS results across Google, Cloudflare, and other resolvers to confirm propagation.
SPF Record Checker
Validate your SPF record and count DNS lookups against the 10-lookup limit.
DMARC Checker
Parse your DMARC policy, check enforcement mode, and verify report destinations.
Live Checkers
Is Website Down?
Check if a website is down for everyone or just you — live HTTP probe from our infrastructure.
SSL Certificate Checker
Analyze SSL/TLS configuration, certificate chain, expiry, and get a security grade.
Website Response Time
Measure DNS, TCP, TLS, TTFB, and download time breakdown for any URL.
Planning
On-Call Rotation Planner
Plan weekly on-call rotations visually and export to iCal or JSON.
Need continuous monitoring?
These tools are for one-time checks. DevHelm monitors your services every 30 seconds from 4 global regions, with instant alerts when something breaks. Free tier includes 50 monitors.
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