Open Library

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Category: Knowledge · Auth: none · Status today: HTTP_ERR (HTTP 503) · 9692 ms

Example request

This is the exact probe the sentinel runs daily — one read-only GET:

curl -s 'https://openlibrary.org/isbn/9780140328721.json'

Example output

No response captured — status was HTTP_ERR at 2026-08-16 00:29 UTC.

Checked 2026-08-16 00:29 UTC by the Free Tier Sentinel. Machine-readable: api-health.json.