--- title: Edge Runtime description: API Reference for the Edge Runtime. url: "https://nextjs.org/docs/app/api-reference/edge" version: 16.2.2 lastUpdated: 2026-04-02 prerequisites: - "API Reference: /docs/app/api-reference" --- Next.js has two server runtimes you can use in your application: * The **Node.js Runtime** (default), which has access to all Node.js APIs and is used for rendering your application. * The **Edge Runtime** which contains a more limited [set of APIs](#reference), used in [Proxy](/docs/app/api-reference/file-conventions/proxy). ## Caveats * The Edge Runtime does not support all Node.js APIs. Some packages may not work as expected. * The Edge Runtime does not support Incremental Static Regeneration (ISR). * Both runtimes can support [streaming](/docs/app/api-reference/file-conventions/loading) depending on your deployment adapter. ## Reference The Edge Runtime supports the following APIs: ### Network APIs | API | Description | | ------------------------------------------------------------------------------- | --------------------------------- | | [`Blob`](https://developer.mozilla.org/docs/Web/API/Blob) | Represents a blob | | [`fetch`](https://developer.mozilla.org/docs/Web/API/Fetch_API) | Fetches a resource | | [`FetchEvent`](https://developer.mozilla.org/docs/Web/API/FetchEvent) | Represents a fetch event | | [`File`](https://developer.mozilla.org/docs/Web/API/File) | Represents a file | | [`FormData`](https://developer.mozilla.org/docs/Web/API/FormData) | Represents form data | | [`Headers`](https://developer.mozilla.org/docs/Web/API/Headers) | Represents HTTP headers | | [`Request`](https://developer.mozilla.org/docs/Web/API/Request) | Represents an HTTP request | | [`Response`](https://developer.mozilla.org/docs/Web/API/Response) | Represents an HTTP response | | [`URLSearchParams`](https://developer.mozilla.org/docs/Web/API/URLSearchParams) | Represents URL search parameters | | [`WebSocket`](https://developer.mozilla.org/docs/Web/API/WebSocket) | Represents a websocket connection | ### Encoding APIs | API | Description | | ----------------------------------------------------------------------------------- | ---------------------------------- | | [`atob`](https://developer.mozilla.org/en-US/docs/Web/API/atob) | Decodes a base-64 encoded string | | [`btoa`](https://developer.mozilla.org/en-US/docs/Web/API/btoa) | Encodes a string in base-64 | | [`TextDecoder`](https://developer.mozilla.org/docs/Web/API/TextDecoder) | Decodes a Uint8Array into a string | | [`TextDecoderStream`](https://developer.mozilla.org/docs/Web/API/TextDecoderStream) | Chainable decoder for streams | | [`TextEncoder`](https://developer.mozilla.org/docs/Web/API/TextEncoder) | Encodes a string into a Uint8Array | | [`TextEncoderStream`](https://developer.mozilla.org/docs/Web/API/TextEncoderStream) | Chainable encoder for streams | ### Stream APIs | API | Description | | ------------------------------------------------------------------------------------------------------- | --------------------------------------- | | [`ReadableStream`](https://developer.mozilla.org/docs/Web/API/ReadableStream) | Represents a readable stream | | [`ReadableStreamBYOBReader`](https://developer.mozilla.org/docs/Web/API/ReadableStreamBYOBReader) | Represents a reader of a ReadableStream | | [`ReadableStreamDefaultReader`](https://developer.mozilla.org/docs/Web/API/ReadableStreamDefaultReader) | Represents a reader of a ReadableStream | | [`TransformStream`](https://developer.mozilla.org/docs/Web/API/TransformStream) | Represents a transform stream | | [`WritableStream`](https://developer.mozilla.org/docs/Web/API/WritableStream) | Represents a writable stream | | [`WritableStreamDefaultWriter`](https://developer.mozilla.org/docs/Web/API/WritableStreamDefaultWriter) | Represents a writer of a WritableStream | ### Crypto APIs | API | Description | | ------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------- | | [`crypto`](https://developer.mozilla.org/docs/Web/API/Window/crypto) | Provides access to the cryptographic functionality of the platform | | [`CryptoKey`](https://developer.mozilla.org/docs/Web/API/CryptoKey) | Represents a cryptographic key | | [`SubtleCrypto`](https://developer.mozilla.org/docs/Web/API/SubtleCrypto) | Provides access to common cryptographic primitives, like hashing, signing, encryption or decryption | ### Web Standard APIs | API | Description | | --------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | [`AbortController`](https://developer.mozilla.org/docs/Web/API/AbortController) | Allows you to abort one or more DOM requests as and when desired | | [`Array`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array) | Represents an array of values | | [`ArrayBuffer`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer) | Represents a generic, fixed-length raw binary data buffer | | [`Atomics`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Atomics) | Provides atomic operations as static methods | | [`BigInt`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/BigInt) | Represents a whole number with arbitrary precision | | [`BigInt64Array`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/BigInt64Array) | Represents a typed array of 64-bit signed integers | | [`BigUint64Array`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/BigUint64Array) | Represents a typed array of 64-bit unsigned integers | | [`Boolean`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean) | Represents a logical entity and can have two values: `true` and `false` | | [`clearInterval`](https://developer.mozilla.org/docs/Web/API/WindowOrWorkerGlobalScope/clearInterval) | Cancels a timed, repeating action which was previously established by a call to `setInterval()` | | [`clearTimeout`](https://developer.mozilla.org/docs/Web/API/WindowOrWorkerGlobalScope/clearTimeout) | Cancels a timed, repeating action which was previously established by a call to `setTimeout()` | | [`console`](https://developer.mozilla.org/docs/Web/API/Console) | Provides access to the browser's debugging console | | [`DataView`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/DataView) | Represents a generic view of an `ArrayBuffer` | | [`Date`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Date) | Represents a single moment in time in a platform-independent format | | [`decodeURI`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/decodeURI) | Decodes a Uniform Resource Identifier (URI) previously created by `encodeURI` or by a similar routine | | [`decodeURIComponent`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/decodeURIComponent) | Decodes a Uniform Resource Identifier (URI) component previously created by `encodeURIComponent` or by a similar routine | | [`DOMException`](https://developer.mozilla.org/docs/Web/API/DOMException) | Represents an error that occurs in the DOM | | [`encodeURI`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/encodeURI) | Encodes a Uniform Resource Identifier (URI) by replacing each instance of certain characters by one, two, three, or four escape sequences representing the UTF-8 encoding of the character | | [`encodeURIComponent`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/encodeURIComponent) | Encodes a Uniform Resource Identifier (URI) component by replacing each instance of certain characters by one, two, three, or four escape sequences representing the UTF-8 encoding of the character | | [`Error`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error) | Represents an error when trying to execute a statement or accessing a property | | [`EvalError`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/EvalError) | Represents an error that occurs regarding the global function `eval()` | | [`Float32Array`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Float32Array) | Represents a typed array of 32-bit floating point numbers | | [`Float64Array`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Float64Array) | Represents a typed array of 64-bit floating point numbers | | [`Function`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Function) | Represents a function | | [`Infinity`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Infinity) | Represents the mathematical Infinity value | | [`Int8Array`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Int8Array) | Represents a typed array of 8-bit signed integers | | [`Int16Array`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Int16Array) | Represents a typed array of 16-bit signed integers | | [`Int32Array`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Int32Array) | Represents a typed array of 32-bit signed integers | | [`Intl`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Intl) | Provides access to internationalization and localization functionality | | [`isFinite`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/isFinite) | Determines whether a value is a finite number | | [`isNaN`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/isNaN) | Determines whether a value is `NaN` or not | | [`JSON`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/JSON) | Provides functionality to convert JavaScript values to and from the JSON format | | [`Map`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Map) | Represents a collection of values, where each value may occur only once | | [`Math`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Math) | Provides access to mathematical functions and constants | | [`Number`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number) | Represents a numeric value | | [`Object`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object) | Represents the object that is the base of all JavaScript objects | | [`parseFloat`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/parseFloat) | Parses a string argument and returns a floating point number | | [`parseInt`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/parseInt) | Parses a string argument and returns an integer of the specified radix | | [`Promise`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Promise) | Represents the eventual completion (or failure) of an asynchronous operation, and its resulting value | | [`Proxy`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Proxy) | Represents an object that is used to define custom behavior for fundamental operations (e.g. property lookup, assignment, enumeration, function invocation, etc) | | [`queueMicrotask`](https://developer.mozilla.org/docs/Web/API/queueMicrotask) | Queues a microtask to be executed | | [`RangeError`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/RangeError) | Represents an error when a value is not in the set or range of allowed values | | [`ReferenceError`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/ReferenceError) | Represents an error when a non-existent variable is referenced | | [`Reflect`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Reflect) | Provides methods for interceptable JavaScript operations | | [`RegExp`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/RegExp) | Represents a regular expression, allowing you to match combinations of characters | | [`Set`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Set) | Represents a collection of values, where each value may occur only once | | [`setInterval`](https://developer.mozilla.org/docs/Web/API/setInterval) | Repeatedly calls a function, with a fixed time delay between each call | | [`setTimeout`](https://developer.mozilla.org/docs/Web/API/setTimeout) | Calls a function or evaluates an expression after a specified number of milliseconds | | [`SharedArrayBuffer`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/SharedArrayBuffer) | Represents a generic, fixed-length raw binary data buffer | | [`String`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String) | Represents a sequence of characters | | [`structuredClone`](https://developer.mozilla.org/docs/Web/API/Web_Workers_API/Structured_clone_algorithm) | Creates a deep copy of a value | | [`Symbol`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Symbol) | Represents a unique and immutable data type that is used as the key of an object property | | [`SyntaxError`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/SyntaxError) | Represents an error when trying to interpret syntactically invalid code | | [`TypeError`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/TypeError) | Represents an error when a value is not of the expected type | | [`Uint8Array`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array) | Represents a typed array of 8-bit unsigned integers | | [`Uint8ClampedArray`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Uint8ClampedArray) | Represents a typed array of 8-bit unsigned integers clamped to 0-255 | | [`Uint32Array`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Uint32Array) | Represents a typed array of 32-bit unsigned integers | | [`URIError`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/URIError) | Represents an error when a global URI handling function was used in a wrong way | | [`URL`](https://developer.mozilla.org/docs/Web/API/URL) | Represents an object providing static methods used for creating object URLs | | [`URLPattern`](https://developer.mozilla.org/docs/Web/API/URLPattern) | Represents a URL pattern | | [`URLSearchParams`](https://developer.mozilla.org/docs/Web/API/URLSearchParams) | Represents a collection of key/value pairs | | [`WeakMap`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/WeakMap) | Represents a collection of key/value pairs in which the keys are weakly referenced | | [`WeakSet`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/WeakSet) | Represents a collection of objects in which each object may occur only once | | [`WebAssembly`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/WebAssembly) | Provides access to WebAssembly | ### Next.js Specific Polyfills * [`AsyncLocalStorage`](https://nodejs.org/api/async_context.html#class-asynclocalstorage) ### Environment Variables You can use `process.env` to access [Environment Variables](/docs/app/guides/environment-variables) for both `next dev` and `next build`. ### Unsupported APIs The Edge Runtime has some restrictions including: * Native Node.js APIs **are not supported**. For example, you can't read or write to the filesystem. * `node_modules` *can* be used, as long as they implement ES Modules and do not use native Node.js APIs. * Calling `require` directly is **not allowed**. Use ES Modules instead. The following JavaScript language features are disabled, and **will not work:** | API | Description | | ------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------- | | [`eval`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/eval) | Evaluates JavaScript code represented as a string | | [`new Function(evalString)`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Function) | Creates a new function with the code provided as an argument | | [`WebAssembly.compile`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/WebAssembly/compile) | Compiles a WebAssembly module from a buffer source | | [`WebAssembly.instantiate`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/WebAssembly/instantiate) | Compiles and instantiates a WebAssembly module from a buffer source | In rare cases, your code could contain (or import) some dynamic code evaluation statements which *cannot be reached at runtime* and which cannot be removed by treeshaking. You can relax the check to allow specific files with your Proxy configuration: ```javascript filename="proxy.ts" export const config = { unstable_allowDynamic: [ // allows a single file '/lib/utilities.js', // use a glob to allow anything in the function-bind 3rd party module '**/node_modules/function-bind/**', ], } ``` `unstable_allowDynamic` is a [glob](https://github.com/micromatch/micromatch#matching-features), or an array of globs, ignoring dynamic code evaluation for specific files. The globs are relative to your application root folder. Be warned that if these statements are executed on the Edge, *they will throw and cause a runtime error*. --- For a semantic overview of all documentation, see [/docs/sitemap.md](/docs/sitemap.md) For an index of all available documentation, see [/docs/llms.txt](/docs/llms.txt)