Congressional Stock Brain vs Marketstack

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

Uptime · 30d
Uptime · 90d100%100%
Uptime · 30d100%100%
P50 · ms385470
P95 · ms17674068
AuthnoneapiKey
CORSyesno
HTTPSyesyes
Card requirednono
Commercial useunclearunclear
Data licenseUnverifiedUnverified
Free tierFree — limits not publishedFree tier — key may be required
Rate limitUnpublishedUnpublished
In directory since2026-07-052026-07-05
operationalpartialdownno data

Congressional Stock Brain vs Marketstack: common questions

Which is more reliable, Congressional Stock Brain or Marketstack?

Both are neck-and-neck — Congressional Stock Brain and Marketstack each measure 100% uptime over 90 days on our probe schedule. Reliability here is verified from our own scheduled checks; use the 30-day bars above to see which has been steadier lately.

Which is faster, Congressional Stock Brain or Marketstack?

Congressional Stock Brain has the lower median latency in our checks — Congressional Stock Brain responds in 385 ms versus Marketstack at 470 ms (P50). Tail latency (P95) is in the table above; for most workloads the median is the number that shapes how the API feels.

Do Congressional Stock Brain and Marketstack need an API key?

Congressional Stock Brain needs no key, while Marketstack requires a free API key. If you want to start calling without signup, reach for Congressional Stock Brain first.

Can I call Congressional Stock Brain and Marketstack from the browser?

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

Are Congressional Stock Brain and Marketstack free for commercial use?

Congressional Stock Brain has unclear commercial terms, and Marketstack 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.