Developer Tools
SHA-1 Generator
Instantly generate SHA-1 hashes from any text.
SHA-1 is not collision-resistant and should not be used for cryptographic security. Computed locally using the Web Crypto API.
Developer Tools
Instantly generate SHA-1 hashes from any text.
SHA-1 is not collision-resistant and should not be used for cryptographic security. Computed locally using the Web Crypto API.
SHA1 (Secure Hash Algorithm 1) is a cryptographic function that produces a fixed 40-character hash from any input. It's deterministic—the same input always produces the same hash—and designed to be one-way, meaning you cannot reverse a hash back to the original input. While SHA1 is considered cryptographically weak for new security applications (replaced by SHA256), it remains useful for file integrity checks, legacy systems, and non-security hashing tasks.
The SHA1 Generator accepts text input and applies the SHA1 algorithm to produce a unique hexadecimal string. Each character in your input, including spaces and special characters, affects the output hash. Changing even a single character produces a completely different hash, making SHA1 useful for detecting file corruption or verifying that data hasn't been tampered with. The process is instant and requires no external accounts or API calls.
| Input | Result | Notes |
|---|---|---|
| hello | aaf4c61ddcc5e8a2dabede0f3b482cd9aea9434d | The word 'hello' always produces this exact 40-character hash every time |
| hello world | 2aae6c35c94fcfb415dbe95f408b9ce91ee846ed | Adding a space changes the hash completely, demonstrating SHA1's sensitivity to input |
| password123 | 482c811da5d5b4bc6d497ffa98491e38 | Common passwords produce predictable hashes that appear in rainbow tables; never use SHA1 for password storage alone |
No. SHA1 is too fast and has known collision weaknesses. For passwords, use bcrypt, Argon2, or PBKDF2, which are deliberately slow and salted. SHA1 works only for file integrity checks, not password storage.
No. SHA1 is cryptographically one-way by design. You cannot recover the input from the output. The only way to verify a match is to hash the suspected input and compare the results.
Researchers have found practical collision attacks on SHA1 (two different inputs producing the same hash), so it's no longer trusted for digital signatures or certificates. SHA256 and SHA3 are recommended for new security-critical work.
SHA1 produces a 40-character hash and is slightly more secure than MD5's 32-character output. Both are considered weak by modern standards; neither should be used for new cryptographic applications.
If you're using a modern browser-based SHA1 generator, it runs entirely in JavaScript on your device with no server interaction, so yes—it works offline once the page is loaded.
A checksum is any fixed-size value computed from data to detect errors or tampering. SHA1 is a type of cryptographic checksum; if a file's SHA1 hash matches the expected hash, the file hasn't been corrupted or altered.