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ReSmush.it vs Simkl

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

APIReSmush.itNEW—SimklNEW—
Uptime · 30d
Uptime · 90d—%—%
Uptime · 30d—%—%
P50 · ms——
P95 · ms——
Authnonenone
CORSyesyes
HTTPSnoyes
Card requirednono
Commercial useunclearunclear
Data licenseN/A — optimization service, not a datasetSimkl terms — user-contributed data
Free tierFree; per-image size cap applies (see docs)Free read routes; client_id for search
Rate limitUnpublished1 req/s documented
In directory since2026-07-052026-07-05
operationalpartialdownno data

ReSmush.it vs Simkl: common questions

Which is more reliable, ReSmush.it or Simkl?

On our scheduled checks, Simkl leads on measured uptime — ReSmush.it at —% versus Simkl 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 ReSmush.it and Simkl need an API key?

Neither needs a paid key — ReSmush.it is callable with no signup, and Simkl is callable with no signup. Both are quick to prototype with; rate limits still apply.

Can I call ReSmush.it and Simkl from the browser?

Only Simkl is browser-friendly — it returns CORS headers over HTTPS. ReSmush.it needs a server-side call or proxy, so factor that into which one fits a front-end project.

Are ReSmush.it and Simkl free for commercial use?

ReSmush.it has unclear commercial terms, and Simkl 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.