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Groundhog Day API vs GrünstromIndex

Same instrument, two spec sheets — measured, not claimed.

APIGroundhog Day APINEW—GrünstromIndexNEW—
Uptime · 30d
Uptime · 90d—%—%
Uptime · 30d—%—%
P50 · ms——
P95 · ms——
Authnonenone
CORSyesyes
HTTPSyesyes
Card requirednono
Commercial useunclearunclear
Data licenseUnverifiedUnverified
Free tierFree — limits not publishedFree under fair-use policy
Rate limitUnpublishedFair-use (paid tiers for higher limits)
In directory since2026-07-052026-07-05
operationalpartialdownno data

Groundhog Day API vs GrünstromIndex: common questions

Which is more reliable, Groundhog Day API or GrünstromIndex?

On our scheduled checks, GrünstromIndex leads on measured uptime — Groundhog Day API at —% versus GrünstromIndex at —% over 90 days. These are our own probe results, not provider claims; the uptime bars above show the day-by-day record for both.

Do Groundhog Day API and GrünstromIndex need an API key?

Neither needs a paid key — Groundhog Day API is callable with no signup, and GrünstromIndex is callable with no signup. Both are quick to prototype with; rate limits still apply.

Can I call Groundhog Day API and GrünstromIndex from the browser?

Yes — both Groundhog Day API and GrünstromIndex send CORS headers over HTTPS, so front-end code can fetch either directly with no backend proxy. That makes them easy to swap in a client-side app while you compare responses.

Are Groundhog Day API and GrünstromIndex free for commercial use?

Groundhog Day API has unclear commercial terms, and GrünstromIndex has unclear commercial terms. We track service terms and the data license as separate fields — see the Commercial use and Data license rows above, and confirm both before shipping either in a paid product.