mswjs/msw

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The industry standard for API mocking in JavaScript.

Stars: 18.2k
Forks: 626
Open beginner issues: 0
Indexed issues: 32
Avg merge: 2h 10m
Merged PRs (30d): 11

Dominant language: TypeScript
License: MIT
Last GitHub push: Sep 8, 2026
Latest indexed: Sep 19, 2026
Contributing guide: Contributing guide
Code of conduct: No code of conduct
Beginner labels: help wanted

Beginner friendly Everything

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32 open issues indexed

ws.link("ws://*") handlers never fire in Chromium/Firefox since 2.12.9 (wildcard host percent-encoded by new URL) Open

Difficulty 3/5 1-2 days Newbie friendliness 72/100

mswjs/msw#2782 · 4 comments · Opened Sep 14, 2026
GraphQL 17 support Open

api:graphql feature

Difficulty 3/5 1-2 days Newbie friendliness 48/100

mswjs/msw#2770 · 1 comment · 2 reactions · Opened Jul 23, 2026
Vitest isolation breaks setupWorker in firefox Open

bug needs:triage scope:browser

Difficulty 4/5 3-5 days Newbie friendliness 55/100

mswjs/msw#2757 · 1 comment · Opened Jun 18, 2026
Two `setupServer()` instances listening at once evaluate every request's handlers twice on Linux — "TypeError: Body is unusable" during handler lookup Open

Difficulty 4/5 3-5 days Newbie friendliness 52/100

mswjs/msw#2756 · 1 comment · Opened Jun 11, 2026
Visit website with domain, cause Refused to set unsafe header "cookie" Open

bug needs:triage scope:browser

Difficulty 3/5 1-2 days Newbie friendliness 55/100

mswjs/msw#2751 · 1 comment · Opened May 24, 2026
Unhandled QuotaExceededError in CookieStore.persist() can crash request handling Open

Difficulty 2/5 1-3 hours Newbie friendliness 74/100

mswjs/msw#2750 · 2 comments · Opened May 24, 2026
Consider `network.pause()` in `NetworkApi` Open

feature

Difficulty 5/5 Over a week Newbie friendliness 38/100

mswjs/msw#2723 · 1 comment · 1 reaction · Opened Apr 20, 2026
[experimental] Pass `NetworkFrameResolutionContext` to `NetworkSource.enable()` Open

Difficulty 4/5 3-5 days Newbie friendliness 45/100

mswjs/msw#2708 · 4 comments · Opened Apr 12, 2026
[experimental] `WebSocketNetworkFrame` cannot be initialized with `WebSocket(Client|Server)ConnectionProtocol` implementations Open

Difficulty 3/5 1-2 days Newbie friendliness 55/100

mswjs/msw#2707 · 2 comments · 1 reaction · Opened Apr 12, 2026
Issue: postinstall breaks during ci installation Open

Difficulty 4/5 3-5 days Newbie friendliness 45/100

mswjs/msw#2704 · 3 comments · 1 reaction · Opened Apr 10, 2026
Improvements (for Vitest) Open

BREAKING CHANGE feature

Difficulty 5/5 Over a week Newbie friendliness 35/100

mswjs/msw#2687 · Opened Mar 28, 2026
Browser websockets can't be re-used within vitest test file. Open

DX needs:discussion scope:browser

mswjs/msw#2648 · 3 comments · 1 reaction · 1 assignee · Opened Dec 31, 2025
MSW stops handling requests after 5 mins in page hidden state Open

bug needs:triage scope:browser

Difficulty 4/5 3-5 days Newbie friendliness 25/100

mswjs/msw#2635 · 16 comments · 2 reactions · Opened Nov 28, 2025
MSW fails to intercept requests in React Native runtime Open

Difficulty 4/5 3-5 days Newbie friendliness 45/100

mswjs/msw#2592 · 3 comments · Opened Sep 26, 2025
Stop managing cookies in node.js Open

feature needs:discussion scope:node

Difficulty 4/5 3-5 days Newbie friendliness 48/100

mswjs/msw#2550 · 3 comments · Opened Jul 14, 2025
Not intercepting socket.io if it gets imported before MSW Open

DX scope:browser

Difficulty 4/5 3-5 days Newbie friendliness 35/100

mswjs/msw#2525 · 3 comments · Opened Jun 5, 2025
Transform WebSocket `connection` on the `ws.link` level Open

api:ws bug needs:discussion

Difficulty 5/5 Over a week Newbie friendliness 25/100

mswjs/msw#2481 · 3 comments · Opened Apr 24, 2025
Support custom WebSocket clients Open

feature help wanted needs:discussion

Difficulty 5/5 Over a week Newbie friendliness 35/100

mswjs/msw#2435 · 6 comments · 4 reactions · Opened Feb 20, 2025
MSW + React + Vite: Failed to HMR Update if MSW active Open

bug needs:triage scope:browser

Difficulty 4/5 3-5 days Newbie friendliness 35/100

mswjs/msw#2401 · 7 comments · 7 reactions · Opened Dec 24, 2024
Following React Native docs does not work and Property 'TransformStream' doesn't exist on React Native (runtime) Open

bug needs:triage scope:node

Difficulty 4/5 3-5 days Newbie friendliness 38/100

mswjs/msw#2367 · 29 comments · 10 reactions · Opened Nov 22, 2024
Bypassed requests miss cookie headers with axios + axios-cookiejar-support Open

bug help wanted scope:node

mswjs/msw#2338 · 10 comments · 1 assignee · Opened Oct 29, 2024
List "graphql" as a peer dependency Open

api:graphql dependencies feature needs:discussion

mswjs/msw#2185 · 6 comments · 1 assignee · Opened Jun 18, 2024
React Native: server.use does not add request handlers Open

bug help wanted needs:triage scope:react-native

Difficulty 4/5 3-5 days Newbie friendliness 35/100

mswjs/msw#2042 · 5 comments · 2 reactions · Opened Feb 16, 2024
MSW fails to start Mock because worker update() fails. Open

bug needs:triage scope:browser

Difficulty 3/5 1-2 days Newbie friendliness 45/100

mswjs/msw#2006 · 3 comments · 1 reaction · Opened Jan 30, 2024
MSW does not mock APIS in react-router-6 loader in the first load Open

bug needs:triage scope:browser

Difficulty 4/5 3-5 days Newbie friendliness 35/100

mswjs/msw#1653 · 27 comments · 7 reactions · Opened Jul 5, 2023
Chrome reloads infinitely when `serviceWorker.options.scope` is set Open

bug needs:triage scope:browser

Difficulty 4/5 3-5 days Newbie friendliness 35/100

mswjs/msw#1627 · 10 comments · 4 reactions · Opened May 25, 2023
Support intercepting `navigate` requests Open

feature

mswjs/msw#1594 · 21 comments · 5 reactions · 1 assignee · Opened Apr 13, 2023
Make worker autoupdate an explicit choice Open

chore DX feature

Difficulty 3/5 1-2 days Newbie friendliness 68/100

mswjs/msw#1297 · 14 comments · 6 reactions · Opened Jun 16, 2022
My app hooks in beforeunload with a confirmation message and then MSW stops working Open

bug potentially solved

mswjs/msw#1105 · 6 comments · 3 reactions · 1 assignee · Opened Feb 16, 2022
MSW leaves cypress component test runner in a loop Open

bug scope:browser with:cypress

Difficulty 4/5 3-5 days Newbie friendliness 35/100

mswjs/msw#744 · 61 comments · 5 reactions · Opened May 22, 2021
Predicate for Logs Open

feature

mswjs/msw#420 · 4 comments · 1 assignee · Opened Oct 9, 2020
Support GraphQL subscriptions Open

feature

Difficulty 5/5 Over a week Newbie friendliness 25/100

mswjs/msw#285 · 6 comments · 57 reactions · Opened Jul 18, 2020

mswjs/msw

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