Caesar Cipher Encoder & Decoder - Free Tool

A Caesar cipher shifts each letter in your text by a fixed number of positions in the alphabet. It's one of the oldest encryption methods, named after Julius Caesar. Use it for puzzles, educational demos, or simple obfuscation. This tool runs in your browser with no data sent to servers.

1. Enter text: Paste the message you want to encode or decode.
2. Set the shift: Choose a number from 1 to 25 (ROT13 uses 13).
3. Encode or decode: Select the direction and click to transform.

• Educational: Teach cryptography basics without complex setup.
• Puzzle creation: Build scavenger hunts, escape rooms, or ARG clues.
• Quick obfuscation: Hide spoilers or surprise messages from casual glances.

Use case 1: Classroom demos

Show students how substitution ciphers work before introducing modern encryption.

Use case 2: Escape room clues

Encode hints with a Caesar shift and give players the key to decode.

Use case 3: Casual obfuscation

Hide punchlines or spoilers in group chats where someone might peek.

Basic example

Input: hello with shift 3
Output: khoor

Advanced example

Input: The quick brown fox jumps over the lazy dog with shift 13 (ROT13)
Output: Gur dhvpx oebja sbk whzcf bire gur ynml qbt

Wrong shift direction

If decoding returns gibberish, try the opposite shift (26 minus your shift).

Non-letter characters

Numbers and symbols stay unchanged. Only A–Z and a–z shift.

• ROT13 (shift 13) decodes itself when applied twice.
• For stronger obfuscation, combine with the Base64 encoder.
• Use the Morse code converter alongside for layered puzzles.

• Apply ROT13 directly with the ROT13 encoder.
• Encode into dots and dashes using the Morse code converter.
• Hash text with the MD5 generator for one-way encoding.

Encoding happens locally in your browser. Caesar ciphers are not secure for sensitive data; use modern encryption for anything private.