Show HN: AI Subroutines – Run automation scripts inside your browser tab

a day ago

Web agents often fail at scaling due to token costs, latency, and non-determinism, with direct API calls hindered by complex authentication mechanisms.
rtrvr solves this by recording and replaying tasks within the user's browser, using the page's own context for auth, CSRF, and fingerprints, avoiding out-of-process rebuilding.
Network captures are ranked and trimmed to identify relevant API calls, filtering out noise like analytics beacons, and avoiding volatile operation identifiers that break on site updates.
Subroutines are deterministic, zero-token tools that agents call with parameters, running as scripts in-page for tasks like sending DMs or posting on social media.
The rtrvr.* helpers provide functions for DOM interactions and authenticated requests, enabling reliable automation without brittle selectors or manual fetch handling.
The approach differs from other tools by keeping execution in-page for native auth handling, aiming to build a community library of Subroutines for common web actions.
Additional features include BYO LLM subscriptions, WhatsApp control, Knowledge Base upgrades, and site analytics via Rover, with the extension available for testing and feedback.

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