FetchGate by simddev

FetchGate bridges an external process — a script, a terminal command, any program — to a live, logged-in browser tab. It lets your code make HTTP requests or run JavaScript inside the tab, inheriting the tab's full session state. No login tokens to harvest, no cookie jars to maintain, no fighting anti-bot measures.

Two modes:

• Fetch mode — your script sends a JSON request (method, url, optional headers); FetchGate executes fetch() inside the tab and returns the raw response (status, headers, body). Requests are authenticated automatically because they originate from the tab itself.

• JS mode — your script sends arbitrary JavaScript; FetchGate runs it in the tab's context and returns the result. Access document, call any page API, read any in-memory state.

Three ready-to-use hosts — no coding required:

All three hosts are available on the GitHub repository (https://github.com/simddev/FetchGate). Pick one and follow INSTALL.md — no writing your own host needed.

• Java TCP host — a persistent server on localhost:9919. Any language can connect with newline-delimited JSON. Stays running for your whole session.
• Python TCP host — identical TCP interface, no Java required. Same callers work unchanged.
• Python embedded host — your Python script is the native host. Firefox launches it directly; no TCP port needed.

Why these permissions?

• "Exchange messages with programs other than Firefox" (nativeMessaging) — how the extension talks to whichever host you install.
• "Access browser tabs" (tabs) — to track which tab is armed and route messages to it.
• "Access your data for all websites" — the content script must be injectable into any site you want to use.

Platform: GNU/Linux. Tested on Firefox and LibreWolf.

Open source: https://github.com/simddev/FetchGate