SpliceTap

Mock, block, delay, redirect and rewrite API requests directly in your browser. Six rule types, GraphQL matching, no proxy needed.

Stop waiting on the backend. SpliceTap intercepts your app's HTTP requests in the browser and answers them however you need — a canned response, a small edit to the real one, a failure, a delay, or a redirect to localhost. No proxy to run, no backend to change, no code to comment out and forget about. Useful the moment the endpoint isn't built yet, the error path won't reproduce, or the network is too fast to catch your loading state. WHAT YOU CAN DO Six rule types cover the things you actually need during development: - Mock — return a synthetic response you define: status code, headers and body. - Patch — let the real request through, then change just a few fields of the response. Uses RFC 7386 JSON Merge Patch, so you can overwrite one key, delete another with null, and leave the rest of the live data untouched. - Block — make a request fail. fetch rejects and XHR fires an error with status 0, exactly like a real network failure looks to your code. - Delay — hold a request for a set number of milliseconds, then let it through unchanged. The honest way to find the spinner you forgot to add. - Redirect — rewrite the URL before it leaves. Regex patterns support $1–$9 captures, so a whole production API can point at localhost with one rule. - Headers and query params — add or strip request/response headers and URL parameters at the network layer. Unblock CORS, override User-Agent, or force a feature flag you can't reach from the UI. TARGET EXACTLY THE RIGHT REQUEST - URL matching by wildcard, regular expression, or plain substring - Filter by HTTP method, or match any - Match on request headers - GraphQL-aware: match a single operationName, so you can mock one query on a shared /graphql endpoint and leave every sibling operation alone Rules are evaluated in your order and the first match wins, so overrides are predictable. RESPONSES THAT AREN'T FROZEN FIXTURES Fourteen placeholders expand on every request — timestamps, dates, GUIDs, random integers, floats, strings, emails and booleans, plus the request's own URL and method. Your UI stops rendering the same stale record every time. SEE WHAT ACTUALLY FIRED Mocked requests never reach the network stack, which means the normal Network tab cannot show them. SpliceTap adds its own DevTools panel that logs every rule that fired — method, URL, rule name, type and status, newest first. BUILT TO STAY OUT OF YOUR WAY - Create a rule from the toolbar popup, or right-click any page to open an in-page editor with the current host already filled in - Alt+Shift+M toggles all mocking; Alt+Shift+N starts a new rule - Export your rules to JSON and import them back, to share a setup or keep a backup - Chaos mode fails a chosen percentage of requests at random, for testing retry and error handling - Light, dark, or follow your system PRIVACY SpliceTap has no account, no backend and no telemetry. There is no server to send anything to. Every rule, setting and statistic stays in Chrome's local extension storage on your own device. Request and response bodies are never recorded — the DevTools log keeps only metadata, and common sensitive query parameters such as tokens and API keys are redacted before a URL is written to it. Nothing is collected, sold or shared. SpliceTap requests access to all sites because there is no way to know in advance which site you'll want to mock — it's the site you're debugging, whatever that happens to be. The interceptor checks your rules before doing anything, and does nothing at all when SpliceTap is switched off. REQUIREMENTS Chrome or Edge 120 or newer. Open source under the MIT License. Source: https://github.com/Nataraaj-Shanmugam/SpliceTap Privacy policy: https://nataraaj-shanmugam.github.io/SpliceTap/privacy.html