Encryption Tools
Encrypt text, create and test passwords, decode JWTs and certificates, and explore classic ciphers from Caesar to Enigma, all processed privately on your device. Learn more
AES Encrypt/Decrypt
Real AES-256-GCM encryption with a password.
AES Mode Comparison
See visually why ECB leaks patterns.
Caesar Cipher
Classic letter-shift cipher, for puzzles and learning.
Diffie-Hellman Key Exchange
Watch Alice & Bob agree a shared secret.
Digital Signature Demonstrator
Sign, verify, and watch tampering get caught.
Enigma Machine Simulator
Real historical wirings, verified vs. Wikipedia's own test vector.
JWT Decoder
Decode a token's header and payload, verify HMAC.
One-Time Pad Cipher
Provably unbreakable, with a random key generator.
Password Generator
Cryptographically random passwords, your rules.
Password Strength Checker
See how strong a password is, on your device only.
Plain Word Password Creator
Memorable passwords made from everyday words.
Playfair Cipher
Classic 5×5 grid digraph cipher.
Rail Fence Cipher
Zigzag transposition, any number of rails.
ROT13
The classic spoiler-hiding cipher.
RSA Key Pair Generator
Real public/private key pair, PEM format.
Steganography Tool
Hide text in a PNG's pixels, verified round-trip.
Substitution Cipher Solver/Encoder
Encode or interactively solve a cipher.
TOTP/2FA Code Generator
The live 6-digit code from a Base32 secret.
Vigenère Cipher
Keyword-based cipher, stronger than Caesar.
X.509 Certificate/PEM Decoder
Subject, issuer, validity — matched vs. openssl.
XOR Cipher
Repeating-key XOR, output as hex.
Encryption, password and cipher tools that never leave your browser
Every tool here runs on your own device using your browser's built-in cryptography, so the text, keys and passwords you type are never uploaded. For real protection, the AES Encrypt/Decrypt tool locks text with AES-256-GCM and a password, and the Password Generator creates truly random passwords. The Password Strength Checker shows how long a password would really survive an attack, not just whether it has a capital letter. Need something you can remember for a low-stakes login? The Plain Word Password Creator builds one from everyday words.
Developers and IT staff will find tools for everyday security work. The JWT Decoder reads a token's claims and verifies its signature. The X.509 Certificate Decoder shows which domains a certificate covers and when it expires. The TOTP Generator produces two-factor codes from a secret, and the RSA Key Generator creates real key pairs in PEM format. To understand how it all works, the Diffie-Hellman Demo, Digital Signature Demo and AES Mode Comparison show the ideas behind HTTPS step by step.
And for puzzles, school projects and history lovers, there's a full set of classic ciphers. Start with the Caesar Cipher and ROT13, then try the Vigenère, Playfair and Rail Fence ciphers. Crack a puzzle by letter frequency with the Substitution Cipher Solver, or recreate wartime messages on the Enigma Simulator, which uses the real rotor wirings. The One-Time Pad shows the only cipher that's mathematically unbreakable, and the Steganography Tool hides a message inside an ordinary-looking picture.
Questions and answers
- Which tool should I use to actually protect a message: AES, the One-Time Pad or a classic cipher?
- Use AES Encrypt/Decrypt. It's the same encryption that protects banking and HTTPS, and with a long password it's practical to use and extremely hard to break. The One-Time Pad is unbreakable in theory, but only if the key is truly random, as long as the message, shared in person and never reused, which is impractical for everyday use. The Caesar, Vigenère, Playfair and other classic ciphers can be cracked in seconds, so they're for learning and puzzles only.
- What's the difference between the Password Generator and the Plain Word Password Creator?
- The Password Generator produces a fully random string such as
q7#Rm2!xVp9Lw4zK, about 100 bits of randomness at 16 characters, which is ideal for anything important stored in a password manager. The Plain Word Password Creator joins four or five everyday words, such asGardenMovieTableSilver, which is far easier to remember and type, at around 45 to 55 bits. That's fine for a forum or a loyalty account, but not for email or banking. Run either result through the Password Strength Checker to compare. - How is hiding a message with the Steganography Tool different from encrypting it?
- Encryption scrambles a message so it can't be read without the password, but it's obvious that something is encrypted. Steganography hides the fact that there's a message at all, tucked into the pixels of an ordinary-looking image, but anyone who suspects it and uses a tool like this one can read it. For both secrecy and invisibility, encrypt your message with the AES tool first, then hide the encrypted text in an image.
- Can the JWT Decoder and X.509 Decoder tell me whether something is safe to trust?
- They tell you what's inside and whether the signature checks out, which is most of the job. The JWT Decoder verifies a token's signature with the secret or public key you provide, and flags expired tokens and the dangerous
"alg": "none". The X.509 Decoder shows which domains a certificate covers, whether it has expired, and whether it uses an outdated SHA-1 signature. Neither can check that the issuer itself is trustworthy; your browser or server does that by checking the chain up to a trusted root. - Is the Enigma Simulator accurate enough to decode real wartime messages?
- Yes, for the Army and Air Force Enigma I. It uses the genuine wirings of rotors I to V and reflectors B and C, ring settings, the plugboard and the middle rotor's "double-step", so with the right settings it reproduces historical messages letter for letter. Because Enigma is its own inverse, typing the encrypted text back in with the same starting positions decrypts it. The four-rotor naval M4 isn't included.