Example
Khoor zruog
Caesar Cipher Encoder/Decoder
Encode or decode with the Caesar cipher for any shift value instantly in your browser. Free online Caesar cipher tool with all 25 shifts — no uploads.
Enter the values below, then press Calculate (or press Enter). The calculator updates your results instantly. Try different values to see how your inputs change the outcome.
- Text to transform — enter a value. A typical Text to transform would be Type or paste text here….
- Shift amount — enter a numeric amount.
- Direction — enter a choice from the options.
- Review your results — the key output is highlighted, with supporting figures below.
Loading calculator…
Results
Result
| Detail | Value |
|---|---|
| Effective shift | |
| Letters shifted |
What is this calculator for?
Apply the classic Caesar cipher with a custom shift — shifting each letter forward or backward through the alphabet.
How to Use This Calculator
Enter the values below, then press Calculate (or press Enter). The calculator updates your results instantly. Try different values to see how your inputs change the outcome.
- Text to transform — enter a value. A typical Text to transform would be Type or paste text here….
- Shift amount — enter a numeric amount.
- Direction — enter a choice from the options.
- Review your results — the key output is highlighted, with supporting figures below.
What You'll Need
- Text to transform
- a value · required
- Shift amount
- a numeric amount range 0–25 · required
- Direction
- a choice from the options (Encode (shift forward), Decode (shift backward)) · optional
About This Calculator
The Caesar cipher is one of the simplest encryption techniques: each letter of the alphabet is replaced by a letter a fixed number of positions away. With a shift of 3, A becomes D, B becomes E, and so on.
Use Encode to shift forward, Decode to shift backward. Because the math wraps around the alphabet, a shift of 13 produces ROT13 — the same result in both directions.
Transformation runs locally in your browser.
Worked Examples
Frequently Asked Questions
How do I brute-force a Caesar cipher?
There are only 25 possible shifts. Try decode with each shift from 1–25 and read the plaintext that forms a sensible message.
What if I enter a shift above 25?
The shift is taken modulo 26, so 27 behaves like 1 and 52 behaves like 26 (no change), matching how rotation works.
Is the Caesar cipher secure?
No. With only 25 keys it is trivially broken by hand. It is useful for education and casual obfuscation only.