SHA-1 Hash Generator
SHA-1 produces a 160-bit (40 hex character) digest and was for years the default for Git object IDs, TLS certificates, and file integrity checks. It is computed here with the browser's native Web Crypto API, so it is both fast and exact.
Although SHA-1 is being retired from security-critical roles, it remains common in legacy systems and content addressing. Paste any text below to see its 40-character SHA-1 digest update live — everything happens on your machine, nothing is uploaded.
| Property | Value |
|---|---|
Digest size | 160 bits (20 bytes) |
Hex length | 40 characters |
Block size | 512 bits |
Designed | 1995 (NSA / NIST) |
Secure for new systems? | No — collisions demonstrated (2017) |
hello→aaf4c61ddcc5e8a2dabede0f3b482cd9aea9434dSHA-1 of "hello" is a quick way to confirm an implementation matches the standard.
Frequently asked questions
Why is SHA-1 considered insecure?
In 2017 researchers produced two different PDF files with the same SHA-1 digest (the SHADAttack), proving real-world collisions are feasible. As a result, browsers, certificate authorities, and security standards have deprecated SHA-1 for signatures.
Does Git still use SHA-1?
Historically Git identified every object with SHA-1, and most repositories still do. Git has added a hardened collision-detecting variant and is migrating toward SHA-256, but SHA-1 object IDs remain extremely common in practice.
How long is a SHA-1 hash?
Always 160 bits, which is 40 hexadecimal characters or 20 bytes, regardless of input length.
Is my input sent to a server?
No. The digest is generated in your browser using the built-in Web Crypto API. Your text stays on your device.