HMAC Generator — Free HMAC SHA256 & SHA512 Online Calculator
Free online HMAC generator. Compute HMAC-SHA256, HMAC-SHA512, HMAC-SHA1, and more with a secret key — instantly in your browser, no data sent to any server.
To generate an HMAC, enter your message and secret key, choose a hashing function such as SHA256 and an output encoding, then copy the HMAC shown below.
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HMAC Generator — Free HMAC SHA256 & SHA512 Online Calculator. Free online HMAC generator. Compute HMAC-SHA256, HMAC-SHA512, HMAC-SHA1, and more with a secret key — instantly in your browser, no data sent to any server.
Our free HMAC SHA256 generator computes a cryptographic signature for any message using a secret key.
Supports SHA256, SHA512, SHA384, SHA224, SHA1, MD5, Keccak-512 (the original Keccak, not NIST SHA3), and RIPEMD160 — a wide range of message authentication code algorithms. Output in Hex, Base64, Base64url, or Binary to match your API requirements.
All computation runs locally in your browser — your secret key and plaintext never leave your device. Use it to sign API requests, verify webhooks, or debug HMAC authentication flows. Related tools: Hash Text, JWT Parser, Base64 Converter.
Our free HMAC generator computes a Hash-based Message Authentication Code using any secret key and your choice of algorithm — SHA256, SHA512, SHA384, SHA224, SHA1, MD5, Keccak-512, or RIPEMD160. Output in Hex, Base64, Base64url, or Binary.
All computation runs locally in your browser with no server uploads.
Use Cases Sign API requests and verify webhook payloads Generate HMAC-SHA256 tokens for authentication Validate message integrity with a shared secret Debug and test HMAC implementations Related tools: Hash Text (SHA/MD5) , JWT Parser , Base64 Converter .
Frequently asked questions
How do I generate an HMAC-SHA256 signature?
Type the message in Plain text to compute the hash, enter the Secret key, and keep Hashing function on SHA256 and Output encoding on Hexadecimal. The HMAC of your text updates as you type; click Copy HMAC to copy it.
Which HMAC algorithms are supported?
MD5, RIPEMD160, SHA1, SHA224, SHA256, SHA384, SHA512 and Keccak-512. SHA256 is the default and the usual choice for API signing and webhooks. Keccak-512 is the original Keccak (what crypto-js calls SHA3), so its result differs from HMAC-SHA3-512 in libraries that follow the NIST SHA3 standard.
Which output encoding should I pick?
Choose Hexadecimal for most APIs and webhook signatures, such as GitHub's X-Hub-Signature-256; Base64 when a service expects it, such as Shopify webhooks; Base64-url for URL-safe tokens and JWT-style signatures; or Binary to see the raw bits.
Why doesn't my HMAC match the one from my server?
Check that the message is byte-for-byte identical, including whitespace, line breaks and JSON key order, and that both sides use the same key, algorithm and encoding. The message and key are read as UTF-8 text here, so a key that is itself hex or Base64 encoded gives a different result.
What is the difference between an HMAC and a plain hash?
Anyone can compute a plain hash such as SHA256, while an HMAC mixes in a secret key, so only someone who knows the key can produce or verify it. That makes HMAC suitable for signing API requests and verifying webhooks, but not for storing passwords.
Is my secret key sent anywhere?
No. The HMAC is computed in your browser with the crypto-js library, so the message and the secret key you enter are not uploaded to a server.
How to use this online tool
HMAC Generator — Free HMAC SHA256 & SHA512 Online Calculator is designed for fast browser workflows when you need to format, validate, convert, decode, encode, generate, or inspect data without opening a heavy desktop app. Start with the input field or visible options, review the result, then copy or download the output for the next step.
Private processing in your browser
HMAC Generator — Free HMAC SHA256 & SHA512 Online Calculator keeps the normal processing step local in your browser. That is useful for code snippets, tokens, documents, configuration values, text samples, and other material that should not be sent to a remote service unless you explicitly choose to share it.
When this tool is useful
Use HMAC Generator — Free HMAC SHA256 & SHA512 Online Calculator for repeatable developer tasks, technical documentation, QA checks, quick conversions, debugging, content cleanup, and internal team workflows. The page focuses on clear inputs, immediate feedback, and output that is easy to reuse in code, reports, tickets, emails, or notes.
Practical tips
Before copying the final result, check important details such as spacing, casing, filenames, encoding, token structure, line breaks, or output format. Small checks prevent mistakes when the result is reused in source code, API requests, documentation, spreadsheets, or shared files.