Findings
What 25 free APIs do when nobody is watching
Patterns we found in the stored checks. Everything here is recomputed every 10 minutes from the raw results, so it stays true as the data grows.
Clock-aligned failures
Open-Meteo returns 503 in the first seconds of :00 and :30. A request a minute later works. Includes a 5-second-interval experiment.
Spikiest API: Datamuse Words
Its 95th percentile is 3.5× its median (110 ms vs 387 ms). Worst request: 1628 ms.
Fastest tail: PyPI JSON
95% of requests finish under 175 ms, worst seen 278 ms.
3 of 25 APIs failed at least once this week
Open-Meteo Forecast (16), Wikipedia REST (1), Open Library Search (1)
When to poll each API
Failure rate and latency by minute of the hour: which cron minute to avoid.
Resilient code snippets
Copy-paste JS, Python and curl for each API with timeouts sized from real latency.
The week in free APIs
Auto-written rolling 7-day report: success rate, least reliable, most erratic, incidents.
Silent schema changes
We fingerprint each response shape and flag when an API changes its fields without warning.
Hour-of-day latency
Heatmap of when each API is slowest.
Heartbeat Index
One number for the health of the free-API ecosystem.