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Chronicling America vs Sofiaplan

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

APIChronicling AmericaNEW—SofiaplanNEW—
Uptime · 30d
Uptime · 90d—%—%
Uptime · 30d—%—%
P50 · ms——
P95 · ms——
Authnonenone
CORSnono
HTTPSyesyes
Card requirednono
Commercial useyesunclear
Data licensePublic domain / no known copyright (Library of Congress)Unverified
Free tierFree — public-domain collection dataFree — limits not published
Rate limitLoC throttles heavy crawling (see LoC API policy)Unpublished
In directory since2026-07-052026-07-05
operationalpartialdownno data

Chronicling America vs Sofiaplan: common questions

Which is more reliable, Chronicling America or Sofiaplan?

On our scheduled checks, Sofiaplan leads on measured uptime — Chronicling America at —% versus Sofiaplan 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 Chronicling America and Sofiaplan need an API key?

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

Can I call Chronicling America and Sofiaplan from the browser?

Neither sends browser-friendly CORS headers reliably, so call Chronicling America and Sofiaplan from a server or proxy rather than client-side. The CORS and HTTPS rows above show exactly what we detected for each.

Are Chronicling America and Sofiaplan free for commercial use?

Chronicling America allows commercial use on its free tier, and Sofiaplan 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.