- What is a hash and what is it used for?
- A hash is a fixed-size fingerprint of data: the same input always gives the same hash, but you cannot reverse it to get the original. Hashes are used to verify file integrity (downloads), store passwords (with salt), sign messages (HMAC), and detect duplicates. This tool generates MD5 and SHA hashes in your browser; nothing is uploaded.
- What is the difference between MD5, SHA-1 and SHA-256?
- MD5 is 128-bit and fast but cryptographically broken; use it only for checksums. SHA-1 is 160-bit and also deprecated for security. SHA-256 is 256-bit, secure and widely used (passwords, certificates, Bitcoin). SHA-384 and SHA-512 are longer variants. For new projects prefer SHA-256 or SHA-512; use MD5 only for non-security checksums.
- Is MD5 still safe to use?
- MD5 is not safe for passwords or signatures because collisions can be found. It is still fine for non-security uses: checksums of downloads, cache keys, or deduplication. This tool offers MD5 for compatibility with legacy systems and simple checksums; for security-critical uses choose SHA-256 or SHA-512.
- What is SHA-256 and why is it widely used?
- SHA-256 is a 256-bit cryptographic hash in the SHA-2 family. It is fast, secure and supported everywhere (browsers, servers, APIs). It is used for TLS certificates, password hashing (with salt), blockchain, and file integrity. This tool computes it in the browser via the Web Crypto API with no server upload.
- What is HMAC and when should I use it?
- HMAC (Hash-based Message Authentication Code) combines a secret key with the data before hashing, so only someone with the key can produce the same hash. It is used for API signing, request verification and secure tokens. Enable HMAC mode, enter your secret key, and the tool will compute HMAC-SHA256 of your text.
- How do I verify a file's integrity with a hash?
- After downloading a file, open the File tab, drop the file, and wait for the hashes. Compare the SHA-256 (or the algorithm the publisher uses) with the value they provide. If they match, the file is unchanged. Use the compare field to paste the expected hash and see a clear match or no-match result.
- Can I reverse a hash to get the original text?
- No. Hash functions are one-way: from the hash you cannot recover the input. The only way to 'crack' a hash is to try many inputs (brute force or wordlists) and see if the hash matches. That is why strong, unique passwords matter: short or common ones can be guessed by such attacks.
- Is it safe to hash passwords with this tool?
- Hashing a password here is safe for learning or one-off checks; the value never leaves your device. For real applications, passwords should be hashed on the server with a slow algorithm (e.g. bcrypt, Argon2) and a unique salt. Do not send passwords to any website; use this tool only for testing or local verification.
