Verify any routing number
in under a second.
Check4Real validates ABA routing numbers using the official Mod-10 algorithm and cross-references the public Federal Reserve E-Payments directory. No accounts, no logs, no tracking.
How it works
Three layers of verification, in real time.
Each request runs through structural validation, the ABA check-digit algorithm, and a directory lookup — entirely on the server, with nothing stored on disk.
Structural validation
Confirms a 9-digit numeric format and verifies the leading prefix matches a valid Federal Reserve district.
Mod-10 check digit
Applies the ABA's weighted Mod-10 algorithm: 3·(d1+d4+d7) + 7·(d2+d5+d8) + (d3+d6+d9) ≡ 0 (mod 10).
Directory lookup
Cross-references the official Federal Reserve E-Payments directory to surface bank name, location, and contact.
Built on the right primitives
Bank-grade methodology, without the friction.
We don't guess. Verification is grounded in published ABA standards and the Federal Reserve's public directory — the same primitives banks themselves use.
Privacy by default
Routing numbers are processed in-memory and discarded. No logs, no analytics, no cookies.
Rate-limited fairly
10 verifications per minute per IP keeps the service free and abuse-resistant.
Open, inspectable logic
Mod-10 is deterministic — re-derive the same result yourself anytime.
29,000+
U.S. financial institutions
<200ms
Average response time
0
Records stored on our servers
100%
Free, no account needed
const sum = 3*(d[0]+d[3]+d[6])
+ 7*(d[1]+d[4]+d[7])
+ (d[2]+d[5]+d[8]);
return sum % 10 === 0;Does Check4Real guarantee a check is real?
No tool can. Verifying a routing number proves the bank exists and the number is well-formed — not that the issuer has funds or that the check itself is authentic. Always confirm with your bank before depositing.
Where does the bank data come from?
We use the public Federal Reserve E-Payments directory (FedACH/Fedwire) as the authoritative source, supplemented by the BankRouting.io API for enriched lookups.
Do you store any data I enter?
No. Routing numbers are processed in-memory and discarded immediately after the response is returned. We don't use cookies, analytics, or any tracking.
Is there a rate limit?
Yes — 10 requests per minute per IP. This keeps the service free and abuse-resistant. If you need higher throughput, contact us.
Can I use this commercially?
Check4Real is provided as an informational utility. For production payment systems, you should use a licensed provider with SLAs and a contractual data source.
Informational use only
Verification confirms a routing number's structure and the issuing bank — it does not guarantee check authenticity or available funds. Always verify with your bank before accepting or depositing a check.