HTTP Debug Proxy Inspector is a Linux alternative to Fiddler Classic for inspecting and debugging web and API traffic. It runs a real local HTTP proxy (default 127.0.0.1:8888) and logs every request and response that passes through it.

FEATURES:

• Session list with method, URL, status, body size, timing (connect / wait / receive), full request and response headers and bodies (gzip/deflate are decoded for viewing, JSON is pretty-printed).
• HTTPS: by default CONNECT requests are tunnelled and only the host, the bytes sent/received and the duration are shown - the encrypted content is NOT decrypted. Optional HTTPS decryption creates a local CA with the openssl binary; it only works for clients where you explicitly import and trust that CA certificate (export button provided). HTTP/1.1 only.
• Rules that really modify live traffic: block URL (403), set/remove request headers, set response headers, regex replace of request/response bodies, override response status.
• Request and response breakpoints: the connection is paused until you edit the raw message and resume it, or abort it.
• Composer: build or replay any captured request (directly or through the proxy so rules apply).
• Export the captured session to HAR 1.2 JSON.

Point your browser, curl (export http_proxy / https_proxy) or any app to the proxy address. The app does not change system proxy settings for you. Limitations: WebSocket/Upgrade and HTTP/2 are not proxied in decryption mode; responses are buffered before they are forwarded (no streaming).

A Linux alternative to Fiddler Classic. Not affiliated with or endorsed by Progress Software Corporation or Telerik.

Support development: https://buymeacoffee.com/thanhnv128b