Is SHA-1 safe to use for security?
No. SHA-1 was deprecated by NIST in 2011. Practical collision attacks exist (SHAttered, 2017). Do not use SHA-1 for digital signatures, certificates, or password hashing. Use SHA-256 or SHA-3.
SHA1 Hash Tool generates SHA-1 message digests from any text input, producing a 40-character hexadecimal hash in your browser. While SHA-1 is deprecated for security-critical applications, it remains widely used in Git (every commit, tree, and blob object is SHA-1 identified), OAuth 1.0 HMAC-SHA1 signatures, legacy certificate fingerprinting, and older API checksum systems.
SHA-1 (Secure Hash Algorithm 1) processes input through a 160-bit compression function, producing a 40-character hex digest. Practical collision attacks were demonstrated by Google in 2017 (SHAttered), making SHA-1 unsuitable for digital signatures and TLS certificates. For cryptographic security, use SHA-256 or SHA-512.
No. SHA-1 was deprecated by NIST in 2011. Practical collision attacks exist (SHAttered, 2017). Do not use SHA-1 for digital signatures, certificates, or password hashing. Use SHA-256 or SHA-3.
Git uses SHA-1 for content addressing (not authentication), and is transitioning to SHA-256 (git config objectFormat sha256). For content fingerprinting, SHA-1's collision resistance is sufficient in this context.
40 hexadecimal characters (160 bits), always the same length regardless of input size.
No. Hashing runs entirely in your browser using the Web Crypto API. Your input never leaves your device.
SHA-256 for general integrity checks, SHA-3 for highest security, and bcrypt/Argon2 for password hashing.
Yes, completely free. No account required.
Tool workspace
Free SHA-1 hash generator online — instantly compute SHA1 checksums for any string. Used for Git object IDs, legacy checksums, and OAuth1 signature verification. No login required.
Input
hello
Output
aaf4c61ddcc5e8a2dabede0f3b482cd9aea9434d