Felo

Atbash Cipher Translator Online

Encode or decode text with the Atbash cipher by swapping each English letter for its reverse-alphabet partner (a↔z, b↔y, m↔n). Case, spaces, digits, and punctuation are preserved, and every result includes a worked example plus a round-trip check. Try it online.

What is Atbash Cipher Translator Online?

Atbash Cipher Translator Online is a conversational tool that converts text using the Atbash cipher, a simple substitution where the alphabet is reversed: a becomes z, b becomes y, and so on through m↔n. Because the mapping is reciprocal, the same operation both encodes plaintext into Atbash and decodes Atbash back into plaintext. You paste text, say whether you want to encode or decode (or let the agent infer it), and get the converted text in a copyable block along with a short explanation.

Key Features

Exact reciprocal mapping. Every English letter is swapped for its reverse-alphabet partner using the full 26-letter table, so attack becomes zggzxp and zggzxp becomes attack.
Case and punctuation preserved. Uppercase stays uppercase, lowercase stays lowercase, and spaces, digits, and punctuation pass through unchanged, so Hello, World! 2024 becomes Svool, Dliow! 2024.
Direction handling. Tell the agent to encode or decode; if you do not say, it defaults to encoding and states that assumption so you can ask for the reverse.
Worked example and round-trip check. Each result includes a short before/after example and a verification that converting the output back returns your original letters.
Unsupported-character report. Letters outside A–Z, such as accented characters or non-Latin scripts, are kept in place and listed so nothing is silently dropped.

How to Use

Paste your text and state the direction, for example: "Encode this with Atbash: Meet me at the library at noon."
Read the converted text in the code block, then copy it. If you asked for a decode, the same block holds the plaintext.
Check the round-trip note. If any characters were left unchanged, the agent lists them so you know exactly what was and was not substituted.

Example Use Cases

Decoding an Atbash cipher puzzle. You found Gsv jfrxp yildm ulc in a puzzle book and want the plaintext: the agent returns The quick brown fox.
Encoding a message for a classroom activity. A teacher wants secret message turned into Atbash for a worksheet and gets hvxivg nvhhztv with the mapping shown.
Checking a hand-written Atbash answer. A student submits Ulii and asks whether it decodes to Four; the agent confirms the letter-by-letter result and flags any mistakes.

Tips for Best Results

Say "encode" or "decode" explicitly when the text could plausibly be either; otherwise the agent assumes encode and tells you so.
Keep the original text intact when pasting. The agent preserves spacing and punctuation, so trimming or reformatting changes the output.
For long passages, split them into paragraphs so each converted block stays easy to copy.

FAQ

What input format does it accept?
Plain text of any length you can paste. The mapping applies only to the 26 English letters; digits, punctuation, spaces, and other characters are preserved and reported.

How accurate is the result?
The substitution is deterministic: each A–Z letter maps to exactly one partner and back. Accuracy depends only on the input text, and the round-trip check confirms the mapping was applied consistently.

How is this different from some free text tools?
Some free text tools apply the substitution but leave case handling and punctuation passthrough undocumented. This agent states those rules up front, shows a worked example, and reports any characters it did not substitute, so you can verify the output rather than guess.

Does it produce images, fonts, or audio?
No. The output is plain text only. Atbash is a letter substitution, not a font or a sound.

Can it decode any Atbash text?
Yes, for text built from the English alphabet. Because the mapping is reciprocal, decoding uses the identical table as encoding.