Keccak-256 Hasher
Input
Output (Byte32)
About Keccak-256
This Keccak-256 online tool helps you calculate hashes from strings. Perfect for blockchain development, Ethereum address generation, and cryptographic operations. Your data never leaves your browser.
Keccak-256 is the underlying hash function used by Ethereum for address generation, transaction signing, and smart contract operations. Unlike SHA-256, Keccak-256 produces different hash values and is specifically designed for blockchain applications.
Supported Input Formats
- • UTF-8 text - Standard text encoding for web applications
- • UTF-16 text - Unicode text encoding with wider character support
- • Hexadecimal - Hex-encoded data strings
- • Base64 - Base64 encoded data
Common Use Cases
- • Ethereum address generation - Generate Ethereum addresses from public keys
- • Blockchain development - Test and verify hash computations
- • Smart contract testing - Verify contract storage and event hashes
- • Data integrity verification - Ensure data hasn't been tampered with
- • Solidity development - Match keccak256() function outputs
🔒 Privacy First
All Keccak-256 hashing happens 100% in your browser. Your text never leaves your device, never hits our servers, and is never logged or stored. This is true privacy by design.
Unlike other online hash generators that upload your data to remote servers, Formatho tools run entirely client-side. Your intellectual property stays yours.
Frequently Asked Questions
▶ What is Keccak-256?
Keccak-256 is a cryptographic hash function used in Ethereum for address generation and smart contract operations. It produces a 256-bit (32-byte) hash value from any input data.
▶ Is my data secure?
Yes! All processing happens 100% in your browser. Your data never leaves your device. No servers, no logging, no storage. True privacy by design.
▶ How is Keccak-256 different from SHA-256?
Keccak-256 is the winner of the NIST hash function competition and was adopted by Ethereum. SHA-256 is a different algorithm used in Bitcoin and many other applications. They produce different hash outputs for the same input.
▶ Can I use this for production?
Yes! The Keccak-256 implementation here uses the same cryptographic library (viem) used in production Ethereum applications. However, for critical security operations, always verify outputs with multiple sources.
About the Keccak256
Calculate Keccak-256 hashes online - free and private, in your browser. For Ethereum and Solidity developers: verify keccak256() outputs, hash preimages, and check commit-reveal values without anything leaving your machine.
Keccak-256 is the hash at the core of Ethereum: contract addresses derive from it, signatures commit with it, and Solidity keccak256() calls it. It is not SHA-3 - Ethereum adopted Keccak before NIST finalized SHA-3 with different padding, so SHA-3 libraries produce different digests.
Hash UTF-8 text, hex, or Base64 input and get the exact 0x-prefixed digest Solidity produces. Seed phrases, preimages, and commit-reveal values never leave your browser.
Use cases and examples
Verify a Solidity keccak256(abi.encodePacked(...)) call by hashing the same bytes here and comparing digests.
Build commit-reveal schemes: hash your secret value now, reveal it on-chain later.
Confirm that an address was derived from a given public key by reproducing the hash chain.
How to use
- Select the input format: UTF-8 text, hex, or Base64.
- Paste your input - the hash updates as you type.
- Verify the digest matches keccak256() in your contract test.
- Copy the 0x-prefixed result.
Frequently Asked Questions
Is Keccak-256 the same as SHA3-256? ▾
No. Ethereum uses the original Keccak submission; NIST later standardized SHA-3 with different padding. SHA3-256 libraries produce different digests than Solidity keccak256().
Why does my Solidity hash not match? ▾
The usual cause is encoding: keccak256 hashes raw bytes, so a string and its hex representation hash differently. Match the input format here (UTF-8 vs hex) to what abi.encodePacked produces.
Is this tool free to use? ▾
Yes! This tool is 100% free. No signup, no credit card, no limits. It's part of Formatho's privacy-first developer toolkit.
Is my data safe? Does this tool send data to a server? ▾
Absolutely. This tool runs entirely in your browser. Your data never leaves your device. Zero server-side processing, zero tracking.