Tap Code Translator
A tap code translator converts text to and from the knock code prisoners tap through walls: each letter is two numbers, its row and column in a 5×5 grid in which C also stands for K. This one reads taps or digits, tries both coordinate orders and every common grid, and plays the code back as knocks, entirely in your browser.
| 1 | 2 | 3 | 4 | 5 | |
|---|---|---|---|---|---|
| 1 | A | B | C/K | D | E |
| 2 | F | G | H | I | J |
| 3 | L | M | N | O | P |
| 4 | Q | R | S | T | U |
| 5 | V | W | X | Y | Z |
- 5×5, C and K share a cell · row, then columnBest match
HELLO
- 5×5, I and J share a cell · row, then column
HELLO
- 6×6, letters and digits · row, then column
IEMMP
- 6×6, letters and digits · column, then row
NYCCU
- 5×5, C and K share a cell · column, then row
MVCCS
- 5×5, I and J share a cell · column, then row
MVCCS
The square isn't written in the cipher, so every square and both coordinate orders are tried. Spaces aren't encoded, so the text comes back run together.
About Tap Code Translator
The tap code puts the alphabet in a 5×5 grid — A B C D E, F G H I J, L M N O P, Q R S T U, V W X Y Z — and sends each letter as two groups of taps: the row, a short pause, then the column. B is one tap, pause, two taps. K has no cell and is sent as C, which costs almost nothing in practice. Nobody has to memorise the grid either: knowing that the rows start A, F, L, Q and V is enough to count your way to any letter. It's a Polybius square, the ancient Greek device, put to work by prisoners. A Cyrillic version is said to have been used by nihilists in the Russian tsars' prisons, and Arthur Koestler's Darkness at Noon depicts it in 1941. It's best known from the Vietnam War: four American prisoners at Hỏa Lò — the "Hanoi Hilton" — Carlyle "Smitty" Harris, Phillip Butler, Robert Peel and Robert Shumaker introduced it in June 1965, and it spread through the camps because it was quicker to learn than Morse and could be sent through any wall. By convention an X ends a sentence and a K acknowledges. In a puzzle the code turns up as numbers (23 15 31 31 34), as dots, or as a recording of knocks. This translator reads digits however they're grouped and taps as runs of dots, and decodes them with the tap code grid and the other common squares, in both coordinate orders, ranking the readings by how English they look — so a puzzle built on the I/J Polybius square instead still comes out right. Encoding gives you numbers, dots, and a playback of the knocks with the code's real rhythm: quick taps within a number, a pause between the two numbers, a longer one between letters.
What Tap Code Translator does
- Translates text to and from tap code, with K sent as C
- Reads taps as dots or numbers, spaced or run together
- Decodes with every common square and both coordinate orders, best match first
- Plays the code back as knocks with the real rhythm
- Shows the grid, so you can count along
When to reach for Tap Code Translator
- Solving a puzzle or CTF challenge built on tap code
- Learning the code by hearing it tapped
- Writing a message in tap code for a game, a story or an escape room
How to use Tap Code Translator
- 01
Paste the code
Numbers like 23 15 31 31 34, or taps written as dots with spaces or slashes between the numbers.
- 02
Read the best match
Every common square and both coordinate orders are tried; the most English-looking reading comes first. Spaces aren't sent, so words run together.
- 03
Encode and play
Switch to Encode, type a message, and copy the numbers or dots — or press Play to hear it knocked.
When to use Tap Code Translator vs alternatives
| Alternative | Use Tap Code Translator when… | Use the alternative when… |
|---|---|---|
| A tap code chart | you want the numbers turned into text, or don't know whether the puzzle used the tap code grid or a Polybius square. | you're learning the code by heart. |
| Morse code | the message has to survive being knocked through a wall, where long and short sounds are hard to tell apart. | you need speed — Morse is quicker to send once learned. |