diff --git a/package.json b/package.json
index 0a01fa7f..8c6891f7 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,7 @@
 {
   "name": "@netlify/functions",
   "main": "./src/main.js",
+  "types": "./src/main.d.ts",
   "version": "0.3.1",
   "description": "JavaScript utilities for Netlify Functions",
   "files": [
diff --git a/src/function/context.ts b/src/function/context.ts
new file mode 100644
index 00000000..2a9897be
--- /dev/null
+++ b/src/function/context.ts
@@ -0,0 +1,24 @@
+// From https://docs.aws.amazon.com/lambda/latest/dg/nodejs-prog-model-context.html.
+export interface Context {
+  callbackWaitsForEmptyEventLoop: boolean
+  functionName: string
+  functionVersion: string
+  invokedFunctionArn: string
+  memoryLimitInMB: string
+  awsRequestId: string
+  logGroupName: string
+  logStreamName: string
+  identity?: { [key: string]: any }
+  clientContext?: { [key: string]: any }
+
+  getRemainingTimeInMillis(): number
+
+  /** @deprecated Use handler callback or promise result */
+  done(error?: Error, result?: any): void
+  /** @deprecated Use handler callback with first argument or reject a promise result */
+  fail(error: Error | string): void
+  /** @deprecated Use handler callback with second argument or resolve a promise result */
+  succeed(messageOrObject: any): void
+  /** @deprecated Use handler callback or promise result */
+  succeed(message: string, object: any): void
+}
diff --git a/src/function/event.ts b/src/function/event.ts
new file mode 100644
index 00000000..366ab06d
--- /dev/null
+++ b/src/function/event.ts
@@ -0,0 +1,32 @@
+export interface Event {
+  rawUrl: string
+  rawQuery: string
+  path: string
+  httpMethod: string
+  headers: EventHeaders
+  multiValueHeaders: EventMultiValueHeaders
+  queryStringParameters: EventQueryStringParameters | null
+  multiValueQueryStringParameters: EventMultiValueQueryStringParameters | null
+  body: string | null
+  isBase64Encoded: boolean
+}
+
+interface EventHeaders {
+  [name: string]: string | undefined
+}
+
+interface EventMultiValueHeaders {
+  [name: string]: string[] | undefined
+}
+
+interface EventPathParameters {
+  [name: string]: string | undefined
+}
+
+interface EventQueryStringParameters {
+  [name: string]: string | undefined
+}
+
+interface EventMultiValueQueryStringParameters {
+  [name: string]: string[] | undefined
+}
diff --git a/src/function/handler.ts b/src/function/handler.ts
new file mode 100644
index 00000000..01485ffd
--- /dev/null
+++ b/src/function/handler.ts
@@ -0,0 +1,11 @@
+import type { Context } from './context'
+import type { Event } from './event'
+import type { Response } from './response'
+
+export interface HandlerCallback {
+  (error: any, response: Response): void
+}
+
+export interface Handler {
+  (event: Event, context: Context, callback: HandlerCallback): void | Response | Promise<Response>
+}
diff --git a/src/function/index.ts b/src/function/index.ts
new file mode 100644
index 00000000..d69ebc9f
--- /dev/null
+++ b/src/function/index.ts
@@ -0,0 +1,6 @@
+import type { Context } from './context'
+import type { Event } from './event'
+import type { Handler, HandlerCallback } from './handler'
+import { Response } from './response'
+
+export type { Context as HandlerContext, Event as HandlerEvent, Handler, HandlerCallback, Response as HandlerResponse }
diff --git a/src/function/response.ts b/src/function/response.ts
new file mode 100644
index 00000000..d6f2fb11
--- /dev/null
+++ b/src/function/response.ts
@@ -0,0 +1,11 @@
+export interface Response {
+  statusCode: number
+  headers?: {
+    [header: string]: boolean | number | string
+  }
+  multiValueHeaders?: {
+    [header: string]: Array<boolean | number | string>
+  }
+  body: string
+  isBase64Encoded?: boolean
+}
diff --git a/src/main.d.ts b/src/main.d.ts
new file mode 100644
index 00000000..d14af30e
--- /dev/null
+++ b/src/main.d.ts
@@ -0,0 +1 @@
+export * from './function'