ROT13 & Caesar Cipher Encoder/Decoder
Shift letters forward or backward through the alphabet to encode or decode text — defaults to classic ROT13, with a brute-force mode that reveals all 25 possible shifts at once.
All 25 Shifts (Brute Force)
Every possible Caesar shift of your input text, computed live — useful for cracking a cipher when you don't know the shift amount.
How to Use the ROT13 / Caesar Cipher Tool
- Paste or type your text into the input box.
- Set the shift amount (1–25) — it defaults to 13 for classic ROT13.
- Optionally check "Strip non-letter characters" to remove numbers, punctuation, and spaces before shifting.
- Click "Encode" to shift the text forward, or "Decode" to reverse it.
- The result updates in the Result box — click "Copy Result" to copy it to your clipboard.
- Don't know the shift amount? Click "Show All 25 Shifts" to see every possible Caesar shift of your text at once and spot the one that reads correctly.
Frequently Asked Questions
Is this secure encryption?
No — the Caesar cipher is a classic educational and puzzle cipher, not real encryption. There are only 25 possible shift values, so it can be broken by brute force in seconds, even by hand. Use it for fun, wordplay, or spoiler-hiding, not for protecting anything sensitive — for real security needs, check out our Hash Generator or Password Generator instead.
Why is ROT13 special compared to other shift values?
Because the alphabet has 26 letters, a shift of exactly 13 is its own inverse — applying ROT13 twice to any text returns the original text unchanged. That's why ROT13 is a popular convention for hiding spoilers or punchlines online: the same button both encodes and decodes.
Does this preserve punctuation, numbers, and spacing?
Yes — only letters A–Z and a–z are shifted. Numbers, punctuation, spaces, and line breaks all pass through completely unchanged, and each letter's original uppercase or lowercase case is preserved.
How does the Decode button know how to reverse the shift?
It simply re-applies the cipher using 26 minus your chosen shift amount, which is mathematically equivalent to shifting backward by the original amount — so you never have to calculate the inverse shift yourself.
Can I use a shift amount other than 13?
Yes — the shift amount is adjustable from 1 to 25, so this tool works as a general Caesar cipher, not just classic ROT13.
What does "Show All 25 Shifts" do?
It computes and displays every one of the 25 possible Caesar shifts of your input text at once, each in its own row with a Copy button. Since a Caesar cipher only has 25 possible shift values, this lets you crack ciphertext with an unknown shift just by scanning the list for the row that reads as real words — no guessing required.
What does "Strip non-letter characters" do?
When checked, the tool removes everything except letters — numbers, punctuation, and spaces — from your text before shifting, so the Result and the brute-force list show only the shifted letters run together. Leave it unchecked (the default) to preserve your original spacing and punctuation exactly.