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Caesar Cipher Encoder & Decoder

Input
Output
Go to the full Classical Cipher Encoder

Shift encoding

Choose a shift from 0 to 25. Each letter moves that many positions forward in the alphabet: with a shift of 3, HELLO becomes KHOOR. Letters near the end of the alphabet wrap back around to A.

Decoding a known shift

Switch to Decode and enter the same shift used to encode the message. The tool applies the shift in reverse, turning KHOOR back into HELLO when the shift is 3.

Brute-forcing an unknown shift

Since a Caesar cipher only has 26 possible shifts, decoding without knowing the shift just means trying each value in turn with Decode selected until the output reads as plain English.

Frequently Asked Questions

Every letter moves forward in the alphabet by a fixed shift amount, wrapping from Z back to A. A shift of 3 turns HELLO into KHOOR. Spaces, digits, and punctuation are left unchanged.

Switch to Decode and enter the same shift value that was used to encode it. Decoding applies the shift in the opposite direction, so the original text comes back.

There are only 26 possible shifts, so try each one from 0 to 25 with Decode selected. English text is usually recognizable within a few attempts.

No. With only 26 possible shifts, a Caesar-shifted message can be brute-forced by hand in under a minute. Use it for puzzles or learning exercises, not for protecting real information.

Try one of these focused ciphers

Full Classical Cipher Encoder tool
001 ROT13 Encoder & Decoder
002 ROT47 Encoder & Decoder

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