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Nock

Mocks HTTP requests in Node.js so tests can run without calling real servers.

GitHub Download v15.0.5
Stars
13.1k
Forks
783
Licence
MIT
Language
JavaScript
Last update
7 days ago
Type
Library

What it is

Nock is a JavaScript library for Node.js that fakes HTTP responses during testing. It works by overriding Node's built-in HTTP request function, so code that calls external APIs can be tested without contacting those APIs. You describe which requests to expect and what replies to return.

  • Mock a GitHub API call so a test checks how your code handles the response without network access
  • Simulate a server error or a delayed response to see how your code recovers
  • Match request bodies or headers and return different replies on repeated calls to the same URL

Great for

  • Developers writing automated tests for Node.js code that makes HTTP calls
  • Teams who want tests isolated from external services like third-party APIs
  • Projects needing to simulate error responses or delays in a controlled way

Not ideal for

  • Non-developers, since it is a code library that requires writing tests in JavaScript
  • Projects not running on Node.js, because the README describes it specifically for Node.js
  • Anyone needing to test against a real live server, since its purpose is to replace that server
Step-by-step guide: how to use NockInstall, first run, examples, tips and FAQs
MSW vs Nock

How to get it

  1. 1

    Install with a package manager

    You'll need: Node.js

    Install as a dev dependency

    $ npm install --save-dev nock
  2. 2

    Run it

    • Install nock as a dev dependency with npm
    • In a test file, require nock with const nock = require('nock')
    • Call nock with the host URL, then chain .get or .post and .reply to define a mock
    • Run your test suite; requests matching the mock will receive the fake reply
  3. 3

    Get the most out of it

    • Use .persist() when one mock should answer many identical requests
    • Use body matching with strings, objects, RegExp or functions to test specific payloads
    • Use nock.back to record and replay fixtures, as described in the Nock Back section
    • Use .isDone() or .pendingMocks() to confirm expected requests actually happened

Downloads

Source code (.zip)main branch · straight from GitHubRelease v15.0.5Release notes and source

Strengths

  • Widely used, with about 13,000 GitHub stars and an MIT license
  • Flexible matching of hostnames, paths, bodies, query strings and headers
  • Supports persisting or sequencing interceptors and checking whether mocks were used

Trade-offs

  • Interceptors are removed after use by default, so each expected request needs its own setup unless you use persist()
  • The README lists a compatibility table of which Node versions each old release supported, which means version choice matters

How it compares

ProjectStarsTypeLevelUpdatedBest for
nock (this)13.1kLibraryintermediate7 days agoDevelopers writing automated tests for Node.js code that makes HTTP calls
msw18.3kLibraryintermediate20 days agoFrontend developers who need to work before a backend API is ready
axum27.7kLibraryintermediate4 days agoRust developers building HTTP APIs or web services
kratos26kLibraryintermediate5 days agoGo developers building a set of backend services that talk over HTTP or gRPC
validator.js23.7kLibrarybeginner2 months agoJavaScript developers validating form or API input on Node.js
chi23kLibraryintermediate19 days agoGo developers building REST API services

Stats synced from GitHub. The assessment above was drafted with AI from the project's README on 2026-10-29 and may miss recent changes — check the README before relying on a command. MIT licence: free to use, modify and distribute, including commercially, as long as you keep the copyright notice.