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Crypto-Tools

GabSoftware Crypto-Tools: A Free Cryptography Toolbox That Runs Entirely in Your Browser

Need to encrypt a file, verify a digital signature, or inspect a JWT token? GabSoftware Crypto-Tools is a free toolbox that handles all of it, without ever sending your data to a server.

There is nothing to install and no account to create. Open the page, pick a tool, and start working.

Private by design

Many online crypto utilities are black boxes: you paste a secret key into a form and hope the server on the other end isn’t logging it. Crypto-Tools takes a different approach. Every operation runs locally in your browser, so your keys, plaintexts and hashes never leave your machine. There is no backend, no database and no telemetry.

What’s in the toolbox

Encryption

  • AES: encrypt and decrypt with AES in GCM, CBC, CTR or ECB mode, using a raw key or a password through PBKDF2 or Scrypt. ECB is available for compatibility, and the app warns you that it is insecure.
  • RSA-OAEP: generate key pairs, encrypt and decrypt. Keys are exported as standard SPKI and PKCS#8 PEM.

Hashing and key derivation

  • SHA: compute SHA-256, SHA-384 or SHA-512 digests, with an optional comparison field.
  • Checksum: drop a file, get its hash, and optionally download a .sha sidecar file.
  • HMAC: sign and verify messages with HMAC-SHA-256, 384 or 512.
  • KDF: derive keys from passwords with PBKDF2 or Scrypt, with OWASP-recommended parameters.

Key exchange and signatures

  • ECDH and X25519: derive shared secrets, with HKDF stretching and AES-GCM wrapping.
  • ECDSA and Ed25519: generate key pairs, sign data and verify signatures.

Tokens

  • JWT: decode, sign and verify JSON Web Tokens.
  • JWE: decrypt JWE payloads, with RSA-OAEP, ECDH-ES, AES Key Wrap and direct key agreement.
  • JWS: sign and verify arbitrary payloads, including detached mode.

Keys and certificates

  • JWK: convert between JWK and PEM, and inspect key fields.
  • PKCS#7: extract X.509 certificates from .p7b and .p7c bundles, and verify CMS SignedData.
  • Key Info: paste a PEM or DER key or certificate and get a readable breakdown of its fields, including validity dates and SANs for X.509 certificates.

Utilities

  • Encode: convert between Base64, Hex and UTF-8.
  • Random: generate cryptographically secure hex strings, Base64 blobs, UUIDs and memorable passphrases from the EFF wordlist.
  • Data URL: encode and decode data: URIs for files and images.

Built on web standards

Crypto-Tools is built with React and Vite, and relies on the browser’s native Web Crypto API (crypto.subtle). Where that API doesn’t cover something, such as Scrypt, the code still runs locally in the page.

Some tools, such as Ed25519 and X25519, depend on what your browser supports, so we recommend an up-to-date browser.

Who is it for?

Crypto-Tools is aimed at developers, security engineers and technically curious users who need a quick way to:

  • prototype or test cryptographic workflows without writing code
  • inspect tokens, certificates and keys
  • generate secure keys and IVs for their own applications
  • verify signatures or checksums on received files
  • learn how modern cryptographic primitives work, interactively

Try it now at cryptotools.gabsoftware.com