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SHA Hash & HMAC Generator

Generate SHA-1, SHA-256, SHA-384, SHA-512 hashes and HMAC signatures with this free online tool. No sign-up required, runs entirely in your browser.

What Are Hash Functions and HMAC?

A cryptographic hash function takes an arbitrary input and produces a fixed-size digest (fingerprint) that is practically impossible to reverse. SHA-256, for example, always outputs a 256-bit (64 hex character) value regardless of input size. HMAC (Hash-based Message Authentication Code) combines a hash function with a secret key to produce a keyed digest, proving both data integrity and authenticity. HMACs are widely used in API authentication, JWT signing, webhook verification, and secure message passing. The Web Crypto API natively supports SHA-1, SHA-256, SHA-384, and SHA-512 for both plain hashing and HMAC operations.

How to Use This Free Hash & HMAC Generator

  1. Select the Hash or HMAC tab depending on your need.
  2. Choose the hashing algorithm (SHA-1, SHA-256, SHA-384, or SHA-512).
  3. Enter or paste the text you want to hash into the input field.
  4. For HMAC, enter the secret key in the additional key field.
  5. The output appears instantly — toggle uppercase if needed and click Copy.

Common Use Cases for Hashing and HMAC

  • File integrity verification — Compare SHA-256 checksums to verify that a downloaded file has not been tampered with or corrupted during transfer.
  • API webhook signature verification — Services like GitHub, Stripe, and Slack sign webhook payloads with HMAC-SHA256 so you can verify the sender's authenticity.
  • Password hashing pre-check — Quickly compute a SHA hash of a string to understand the output format before implementing server-side password storage (always use bcrypt/scrypt for actual passwords).
  • Digital signature and token validation — JWT tokens and OAuth flows rely on HMAC-SHA256 to sign payloads, ensuring the token has not been altered.

FAQ

Is SHA-256 hashing the same as encryption?
No. Hashing is a one-way function — you cannot recover the original input from the hash. Encryption is two-way and requires a key to decrypt. Hashing is used for integrity checks, not for protecting confidential data in transit.
Why is MD5 not included?
MD5 is cryptographically broken and vulnerable to collision attacks. The Web Crypto API does not support MD5 by design. For any security-sensitive use case, SHA-256 or higher is recommended.
What is the difference between Hash and HMAC?
A plain hash takes only the message as input, while HMAC also requires a secret key. HMAC proves both that the data has not been altered and that it was created by someone who knows the secret key.
Is my data sent to a server?
No. All hashing and HMAC computation happens locally in your browser using the Web Crypto API. No data leaves your device.

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