Reqbreak

Simulate network failures and modify network requests for testing and debugging.

Reqbreak is a developer tool for testing how a web page behaves when its network requests fail, slow down or come back different. Write a rule, choose which requests it matches, and Reqbreak applies it in your own browser. There is no account, no server and no setup outside the extension. WHAT YOU CAN DO • Fail requests with a real network error: offline, connection reset, connection refused, timed out, DNS failure and more. Fail every request, a percentage of them, or only the first few. • Delay requests by a fixed time to test loading states and timeouts. • Mock a response: return your own status code, headers and body without contacting the server. • Modify a response body: replace it, find and replace text, or apply a JSON Patch. Optionally change the status code as well. • Redirect requests to another URL, for example from production to a local server. • Add, change or remove request headers and response headers. • Block requests. MATCHING Each rule matches by URL (wildcard or regular expression), HTTP method and resource type. Rules are ordered and the first match wins. TWO ENGINES, CLEARLY LABELLED • Standard rules (redirect, headers, block) use Chrome's built-in rule engine. They work on the sites you allow, with no banner. • Advanced rules (network error, delay, mock response, modify response body) need Chrome's debugger. You turn the advanced engine on for one tab at a time from the popup. While it is on, Chrome shows a "Reqbreak started debugging this browser" banner. Turn it off, or close the tab, and Reqbreak detaches. Every rule in the editor is labelled Standard or Advanced, so you always know which engine it needs. ALSO INCLUDED • Presets: flaky API, slow network, offline and timeout. • Import and export rules as a JSON file. • An activity log of the last 200 requests the advanced engine handled, kept for the current browser session only. • Light and dark themes, and full keyboard use. PERMISSIONS, IN PLAIN WORDS • Reqbreak has no access to any website when you install it. You allow it one site at a time, and you can remove a site again at any time. • The debugger is attached only to a tab where you switch the advanced engine on. It is never attached on its own, and it pauses only the requests your rules match. • Chrome's install prompt describes the debugger permission in broad terms ("Read and change all your data on all websites"). That wording belongs to the permission itself. Reqbreak uses it only as described above. PRIVACY Reqbreak collects nothing. It has no server, no analytics and no telemetry. Your rules are stored on your computer in Chrome's extension storage and are never sent anywhere. LIMITS TO KNOW ABOUT • Advanced rules do not apply to pages controlled by a service worker, or to requests made inside cross-origin iframes and workers. • Response body rules work on text responses. • Chrome does not let extensions produce ERR_EMPTY_RESPONSE or ERR_NETWORK_CHANGED, so Reqbreak shows them as unavailable instead of imitating them.