Network Modifier

Network Modifier is a frontend API debugging tool that captures and modifies Fetch and XMLHttpRequest traffic in browser tabs you explicitly select. Inspect request and response URLs, methods, headers, bodies, status codes, timing, and rule matches in a standalone dashboard or DevTools panel. Create reusable rules to replace bodies, edit nested JSON fields, change headers or status codes, add latency, simulate failures, pause traffic, and return mock responses. Organise rules into folders and profiles, compare captured responses, simulate network conditions, and import or export rules and HAR files. Page mode modifies Fetch and XHR at the page JavaScript layer. Full mode is optional and uses Chrome's debugger API to modify browser network responses for the selected tab. Full mode displays Chrome's standard debugging banner while attached. All captured traffic and settings remain on the user's device. Network Modifier has no analytics, advertising, tracking, remote code, or developer-operated backend.