THorn HTTP: Intercept & Modify HTTP Requests

Free, local-first HTTP(S) interceptor: redirect URLs, modify headers, inject scripts, mock REST & GraphQL APIs, and more.

THorn HTTP lets you intercept and modify HTTP(S) traffic right in your browser. Everything runs locally: no account, no cloud, no analytics. Rules • Redirect Request: send a URL (or a pattern) to another URL, e.g. production → localhost • Replace String: replace parts of URLs or hosts • Query Param: add, change or remove query parameters • Modify Headers: add, change or remove request and response headers • Modify API Response: mock REST and GraphQL responses • Modify Request Body: override request payloads • Insert Scripts: inject JavaScript or CSS into pages • Cancel Request: block requests • Delay Network Requests: simulate a slow API, a slow CDN or a slow image, script or font • User-Agent: emulate other devices and browsers Also • Record the network traffic of a page and export it as HAR • DevTools panel showing which rules ran on each request • Import and export your rules as JSON, and import rules from other header and redirect tools • Pause everything with one switch Privacy THorn HTTP stores your rules only in your browser and sends no data anywhere. Debugger permission (Chrome and Edge) The "Delay Network Requests" rule can also hold back scripts, styles, images and fonts, to preview skeletons, spinners and a slow CDN. Browsers offer no other way to do this, so THorn HTTP uses the "debugger" permission only for this. It is attached only while you have a Delay rule switched on, uses only the Fetch domain to pause the requests that rule matches, and continues each one unchanged when the delay is up. It never reads, stores or sends page content. While it is attached, Chrome shows its "started debugging this browser" bar; switch the rule off and the bar goes away. Open source THorn HTTP is free software under the GNU AGPLv3. Source code and credits: https://github.com/Thorn-http/thorn-http