HTTP/3 Adapter

This extension enables sending HTTP requests over HTTP/3 (QUIC) by intercepting requests, converting them to HTTP/3, transmitting them to the target, and converting the responses back to a compatible HTTP version for display and analysis.

Features

• Two operating modes: explicit opt-in per request using an X-Http3: 1 header, or automatic HTTP/3 upgrade for all hosts that support it.
• Bulk HTTP/3 support check via a context menu option on proxy history items, with results reported to the Organizer.
• Kettled request mode, triggered by adding X-Kettled: 1, sends the header block exactly as written with no normalization, case folding, or header stripping, and supports escape sequences for special bytes.
• Unsupported Origins tab that lists hosts where the QUIC handshake failed, with the option to clear and retry.
• Configurable connection and handshake timeouts, connection reuse, TLS certificate verification, and optional logging of adapted exchanges to the Output panel.
• Automatic stripping of HTTP/3-forbidden headers (Connection, Keep-Alive, Transfer-Encoding, etc.), with an option to disable stripping for deliberate testing.

Usage

1. Configure the extension mode under Settings → Extensions → HTTP/3 Adapter.
2. To send a specific request over HTTP/3 in Explicit HTTP/3 only mode, add the header X-Http3: 1 to the request before sending it.
3. To upgrade all compatible traffic automatically, switch the mode to Always HTTP/3 where possible; no per-request header is needed.
4. To check whether multiple hosts support HTTP/3, select them in the proxy history, right-click, and choose Check HTTP/3 Support; results appear in the Organizer.
5. To send a kettled request with an exact, unmodified header block, add both X-Http3: 1 and X-Kettled: 1 headers and write the header block as desired, using supported escape sequences for special characters.
6. To review hosts where HTTP/3 handshakes failed, enable the Unsupported Origins tab in settings and inspect or clear the list as needed.
7. To log each adapted request and response, enable Log exchanges to Output in the settings panel.