Encoding & Crypto

Encode and decode Base64, URL components and HTML entities. Hash with SHA-256 or bcrypt, sign a message with HMAC, encrypt text with AES and a passphrase, generate an SSH key pair, read the codes an authenticator produces, and make passwords and UUIDs.

These are the tools people most often paste a real secret into — a live token, a signing key, a password — which is exactly why every one of them runs in the page. The browser does the work with its own cryptographic implementation, and nothing is transmitted. Load a tool, disconnect from the network, and it keeps working.

Certificates are the one thing here you read rather than make. A PEM certificate holds its subject and issuer, every hostname it covers, the key size, the fingerprints and — the field that matters most often — the expiry, with the number of days left.

What a certificate starts from can be made here, though: a signing request for a certificate authority, with an RSA or ECDSA key made in the page or one you already have, every hostname as an alternative name, and the signature checked before it is copied.

Recovery phrases are here too: a BIP39 phrase of 12 to 24 words made from the browser’s cryptographic randomness, a phrase checked word by word and against its checksum, and the seed a wallet derives from it.

Base64 Encode & DecodeEncode text or any file to Base64 and decode it back, with URL-safe output, line wrapping and data URIs. Unicode is handled correctly.URL Encode & DecodePercent encode and decode text for URLs, choosing between escaping a single value or a whole address, and see any URL broken into its parts.UUID GeneratorGenerate UUID v4 and v7, ULIDs, Nano IDs and short IDs in bulk, and inspect any UUID to read its version, variant and creation time.Hash GeneratorHash text or any file with MD5, SHA-1, SHA-256, SHA-512, SHA-3 and CRC32 at once, and check the result against a digest you were given.Password GeneratorGenerate strong passwords or memorable passphrases in your browser, with a clear reading of how long they would take to crack.HTML Entity Encoder & DecoderEncode text for HTML, escaping only what breaks markup or as much as you need, decode entities back, and look up the ones you can never remember.HMAC GeneratorSign a message with a secret key using HMAC-SHA1, SHA256, SHA384 or SHA512, in hex or Base64, and check it against a signature you were given.bcrypt Hash & VerifyHash a password with bcrypt at any cost factor, check a password against an existing hash, and read what a hash is actually made of.AES Encrypt & DecryptEncrypt text with AES-GCM and a passphrase, and decrypt it again. Tampering is detected, and everything happens in your browser.SSH & RSA Key Pair GeneratorGenerate an Ed25519 or RSA key pair in your browser, with the public key ready for authorized_keys, PEM files and the SHA-256 fingerprint.TOTP Code GeneratorGenerate the six-digit codes an authenticator app produces from a Base32 secret, watch them roll over, and check a code against the current window.X.509 Certificate DecoderPaste a PEM certificate and read it: subject, issuer, expiry with days left, every hostname it covers, key size and fingerprints. Nothing is uploaded.htpasswd GeneratorMake a .htpasswd file for Apache or nginx basic auth, with bcrypt hashing in your browser and the server config to go with it.CSR GeneratorMake a certificate signing request and its private key in your browser: RSA or ECDSA, subject and SAN names, checked before you copy, plus the OpenSSL command.BIP39 MnemonicMake, check or decode a BIP39 recovery phrase: 12 to 24 words, checksum checked, typos caught, and the seed derived with an optional passphrase.