Caesar Cipher
Encrypt and decrypt text with the Caesar (shift) cipher using any key 0-25. Includes a brute-force cracker showing all 25 possible decryptions. Case-preserving, instant, and 100% client-side — perfect for cryptography students, CTF challenges, and puzzles.
Loading tool...
What is Caesar Cipher?
The Caesar cipher is one of the oldest known encryption techniques, named after Julius Caesar who used it for military messages. Each letter in the plaintext is replaced by a letter some fixed number of positions down the alphabet, known as the shift or key.
Key Benefits
- Simple to learn
- Visual and instant
- Brute-force cracker built in
- Case preserving
Common Use Cases
- •Cryptography classes
- •CTF challenges
- •Escape rooms
- •Puzzle solving
How to Use the Caesar Cipher
- Choose mode: Select Encrypt or Decrypt.
- Set the shift: Drag the slider to choose a key from 0 to 25.
- Enter text: Type or paste the plaintext or ciphertext.
- Read or crack: Copy the result, or open brute-force to try all 25 keys.
Key Features
- Adjustable shift from 0 to 25 with a live slider
- One-click encrypt/decrypt toggle plus a Swap button
- Brute-force panel listing all 25 possible plaintexts
- Preserves letter case, spaces, and punctuation
- Copy any brute-force candidate with one click
- 100% client-side — no signup, no data leaves the browser