Online HMAC Generator
Generate secure HMAC hashes instantly with our free online HMAC generator. Support for SHA-256, SHA-512, and MD5 with zero data storage.
About HMAC Generator
Calculate Hash-based Message Authentication Codes (HMAC) directly in your browser with our fast, free security utility. Whether you are validating webhooks, debugging REST API authentication, or verifying payload integrity, this tool computes accurate cryptographic signatures using your plaintext message and secret key.
All calculations run entirely on your device using client-side Web Cryptography APIs. Your sensitive payloads and private keys are never transmitted to our servers or stored in any database, ensuring maximum confidentiality for your development workflows.
Key features
- Client-side cryptographic calculation ensures complete privacy
- Supports SHA-256, SHA-512, SHA-1, and MD5 algorithms
- Configurable output formats in hexadecimal or Base64
- Instant signature computation upon input change
- One-click copy button for rapid integration
- No registration or software installation required
How to use HMAC Generator
- Enter or paste your raw message into the input field.
- Type or paste your secret key.
- Select your desired hashing algorithm from the dropdown.
- Choose your preferred output format between Hexadecimal and Base64.
- Copy the generated HMAC hash for your application or API request.
Who is it for?
- API developers validating HMAC authentication headers during integration testing
- Engineers verifying webhook signatures from providers like GitHub, Stripe, or Shopify
- Security auditors cross-referencing message integrity proofs and hash outputs
- DevOps professionals configuring secure server-to-server webhook verification systems
Frequently asked questions
What is an HMAC?
An HMAC (Hash-based Message Authentication Code) is a cryptographic construction that uses a cryptographic hash function and a secret shared key to verify both the data integrity and the authenticity of a message.
Is my secret key sent to your server?
No. The HMAC generation occurs entirely within your browser using JavaScript and the Web Crypto API. Neither your message nor your secret key ever leaves your device.
Which hash algorithms are supported by this HMAC generator?
The tool supports common cryptographic hash algorithms, including SHA-256, SHA-512, SHA-384, SHA-1, and MD5, allowing you to match most standard API authentication specifications.
What is the difference between HMAC and a standard hash?
A standard hash only verifies data integrity and can be generated by anyone who has the message. An HMAC incorporates a secret key, ensuring that only parties possessing the key can generate or verify the signature.
Is this HMAC generator free to use?
Yes. This tool is completely free to use with no account registration or daily generation limits required.