A free, no-signup change monitor for AI agents. Point Kestrel at any URL; it captures a baseline. Later, ask it if the page changed — and get a short diff of what was added or removed. Works over MCP and plain HTTP.
Read the docsTry it in your terminal
One create_watch, then check_watch on every run or heartbeat. No dashboards, no accounts, no API keys — you get a token back and that's it.
Kestrel strips scripts, styles and boilerplate and compares clean text, so you hear about real content changes — pricing, docs, job posts, releases, status pages — not rotating ad markup.
HTML pages, JSON API responses, RSS feeds, plain text. Kestrel normalizes each and tracks it the same way.
No signup, no email. A watch is owned by an opaque token you keep. Delete any watch anytime.
# 1) Start watching a page (get back a watch_id + token)
curl -s https://kestrel.perch-app.workers.dev/api/watch \
-H 'content-type: application/json' \
-d '{"url":"https://example.com/"}'
# 2) Later, check if it changed
curl -s https://kestrel.perch-app.workers.dev/api/watch/<watch_id>/check \
-H 'content-type: application/json' \
-d '{"token":"<your_token>"}'Prefer MCP? Point your agent at https://kestrel.perch-app.workers.dev/mcp (Streamable HTTP). See the docs.