SHA-1 Hash Generator — Free Online SHA1 Tool

SHA-1 (Secure Hash Algorithm 1) was designed by the NSA and published by NIST in 1995. It produces a 160-bit hash displayed as 40 hex characters. While SHA-1 dominated the 2000s — used in SSL/TLS, PGP, SSH, and S/MIME — it's been deprecated for security applications following the SHAttered attack demonstrating practical SHA-1 collisions in 2017.

SHA-1 remains in use for non-security applications: Git object addressing (migrating), legacy system compatibility, file checksums where collision resistance isn't required, and HMAC-SHA1 (which is still secure despite SHA-1's collision weakness because HMAC uses SHA-1 differently). When in doubt, use SHA-256 instead.

This tool uses the browser's Web Crypto API which still supports SHA-1 for compatibility reasons. The computation is native, hardware-accelerated, and all processing occurs client-side.