Is my text sent to a server?

No. The hash is computed locally using your browser's built-in Web Crypto API (crypto.subtle.digest). Your text never leaves your device and nothing is uploaded.

Is SHA-1 still safe to use?

SHA-1 is no longer considered secure against collision attacks and should not be used for digital signatures or password storage. It is still useful for non-security purposes such as file checksums, Git object IDs, and legacy integration where SHA-1 is required.

How long is a SHA-1 hash?

A SHA-1 hash is 160 bits, shown as 40 hexadecimal characters.

Can I reverse a SHA-1 hash back to the original text?

No. SHA-1 is one-way, so there is no formula to recover the input. The only way to find an input is to guess and re-hash, which is why short or common strings can be looked up in precomputed tables.

Why does Git still use SHA-1?

Git uses SHA-1 to name objects like commits and files, where the risk is accidental collisions rather than malicious attacks. Newer Git versions add collision detection, and a transition to SHA-256 is underway.

What is the SHA-1 hash of an empty string?

It is da39a3ee5e6b4b0d3255bfef95601890afd80709. Hashing no input still produces a fixed 40-character digest.

What is the SHA-1 Hash Generator?

Free SHA-1 hash generator that turns any text into a 40-character hexadecimal digest using the browser's built-in Web Crypto API. Runs entirely in your browser — nothing is uploaded to any server. It runs free in your browser on Gera Tools, with nothing uploaded.

SHA-1 Hash Generator

Name: SHA-1 Hash Generator
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

Get one useful tool a week

Like this tool? Enter your email and we'll send you one genuinely useful Gera tool a week — plus a link to come back to this one. No spam, one-click unsubscribe any time.

SHA-1 hash generator

Paste any text and instantly get its SHA-1 digest — a 160-bit value shown as 40 hexadecimal characters. The hash updates as you type, making this handy for checksums, Git object IDs, and legacy integrations that still expect SHA-1.

How it works

The tool encodes your text as UTF-8 bytes and passes them to the browser’s built-in Web Crypto API (crypto.subtle.digest("SHA-1", …)). SHA-1 is a one-way hash: it always produces the same 160-bit output for the same input, the output reveals nothing about the input, and even a one-character change produces a completely different digest. Because the hashing is done by the browser, your text never leaves your device.

Example digests

Input	SHA-1 (40 hex characters)
(empty)	da39a3ee5e6b4b0d3255bfef95601890afd80709
abc	a9993e364706816aba3e25717850c26c9cd0d89d
hello	aaf4c61ddcc5e8a2dabede0f3b482cd9aea9434d

Notice that changing a single character from abc to abd produces an entirely different 40-character string — this is the avalanche effect, a fundamental property of cryptographic hash functions.

When SHA-1 is still appropriate

SHA-1 is broken for collision resistance, meaning it is theoretically possible (and has been demonstrated in research) to construct two different inputs with the same SHA-1 hash. This matters enormously for digital signatures, certificates, and anything relying on the hash to guarantee uniqueness in a security context. Do not use SHA-1 for:

Digital signatures or code-signing certificates (use SHA-256 or SHA-3)
Password storage (use bcrypt, scrypt, or Argon2)
TLS certificate fingerprints in trust decisions

SHA-1 remains appropriate for:

Git object IDs — Git names every commit, tree, blob, and tag by its SHA-1 hash. The risk here is accidental collision, not adversarial attack. Git’s collision detection protects against the known SHAttered attack, and a migration to SHA-256 is in progress but not yet default.
Legacy API integrations — many older APIs and message-queue signatures (for example, some webhook verification schemes) still require HMAC-SHA1. You need SHA-1 to compute what the remote end expects.
Non-security checksums — verifying a downloaded file has not been corrupted in transit is a data-integrity check, not a security check; SHA-1 is fast and sufficient for this.
Cache keys and fingerprinting — hashing a build artifact, a template string, or a configuration blob to detect changes is a common use case that does not involve adversaries.

If you need a security-appropriate alternative, use the SHA-256 generator linked in the related tools below.