Caesar Cipher Translator

Keep English as the source in the main box to apply a shift of 3. Swap the boxes to undo that same shift. In the workbench, choose Encode or Decode before selecting a different key. Encoding moves forward through the alphabet; decoding moves backward by the selected amount. If a friend tells you the message used a shift of 5, decode with 5 rather than trying to compensate by changing the direction several times.

The Caesar Cipher Translator does not infer a secret key from the main text box. Use the workbench when the key is unknown or different from 3.

The alphabet is a loop. With a shift of 3, A becomes D and Z becomes C. Uppercase and lowercase letters keep their case, which makes an encoded name or sentence easier to compare with the source. The workbench changes the result immediately when the shift changes. Try a short word that contains X, Y or Z to see why wrapping is necessary rather than treating the end of the alphabet as an error.

Only the 26 basic Latin letters move. A digit, accent, emoji or punctuation mark stays in its original position; this is not a shift over every Unicode character.

Select “Show all 26 decoding shifts” to list every possible key in numerical order. Read the whole phrase, including the short words and punctuation, before choosing a candidate. A one-letter message can make sense under many keys, and a name may look plausible under more than one. The table deliberately does not add an accuracy score or label a row as the original message. Your surrounding puzzle clues still matter.

Shift 0 is included as a control: it leaves the input unchanged. The Caesar Cipher Translator never deletes that possibility just because the message looks encoded.

ROT13 is a shift of 13 over the same 26-letter alphabet. Applying it twice restores the starting letters because two half-turns make one full turn. Select 13 in the workbench, copy the result, and replace the input with that result to check the rule. This is useful for a short spoiler or a classroom example where both people agree on the convention. It provides obfuscation rather than meaningful protection.

For another shift, restore the message by decoding with the same key. Encoding twice with a key other than 13 generally does not return the original.

Keep an untouched copy of your source message and write down the key separately. Decide whether visible punctuation and word spacing should remain as clues; this implementation retains them. If you remove spaces manually after conversion, remember that the recipient will need to reconstruct those boundaries. For a worksheet, include one worked letter mapping and a clear direction rather than mixing different cipher conventions in the same exercise.

The Caesar Cipher Translator is a single-alphabet shift. A keyword-based Vigenère cipher, a substitution with an arbitrary alphabet or a number code requires a different set of rules.

First check whether the original message was actually English and whether its letters were already shifted. Next confirm the key and direction. If all 26 candidates remain unreadable, the source may use another cipher or contain a copying error. Compare the original characters before removing anything. A missing letter stays missing under every key, and repeated conversion cannot restore information that was not in the supplied message.

The main Caesar Cipher Translator allows 500 input characters. Longer classroom messages can be handled in separate sections with the same key, keeping their order clear.