Tap code translator — knock messages as row and column taps

How to use the tap code translator

1. Choose the Direction: Text → taps or Taps → text.
2. When encoding, pick Show taps as: 2,3 for numbers or .. … for dots.
3. Type into Your text.
4. Read the Result. Letters are separated by a space (two spaces in dot style), and words by a slash.

What it does and when to use it

Tap code is a simple way to send text by knocking. It is best known from American prisoners of war in Vietnam, who used it to talk through cell walls. Today it turns up in escape rooms and scouting games. Because each letter needs at most ten taps and only two counts, it is easy to learn by heart.

It is a signalling code, not a cipher that protects anything. For a written number grid with a keyword, use the Polybius square, which shares J with I instead of dropping K. For signalling with long and short sounds instead of counts, see the Morse code translator, and for touch-based reading there is the Braille translator.

How it works

The tool uses this grid. The row is tapped first, then the column:

Encoding. The text is split into words at spaces. In each word, only letters A to Z are kept and K becomes C. Digits and punctuation are dropped. Number style writes each letter as row,column; dot style writes the row as dots, a space, then the column as dots.

Decoding. Words are split at slashes. If a word contains dots, the tool counts the dots in each space-separated group and reads the groups in pairs. Otherwise it keeps only the digits 1 to 5 and reads them in pairs, so 2,3 and 23 both give H. An odd number of groups or digits gives a message. All of it runs in your browser.

Worked examples

Results from the tool:

Hi there                   →  2,3 2,4 / 4,4 2,3 1,5 4,2 1,5
Kick                       →  1,3 2,4 1,3 1,3
Hi          dot style      →  .. ...  .. ....
4,3 3,4 4,3   decode       →  SOS

In the second line every K and C becomes the same 1,3. The third shows H as two dots and three dots, then I as two dots and four dots. The last line is a distress call: S is row 4, column 3, and O is row 3, column 4.

Limits and tips

• Decoded text is in capitals, and every C may have been a K.
• Numbers cannot be sent. Spell them out as words before encoding.
• Keep every dot group to between one and five dots. Larger groups are not valid tap code, so the decoder shows a ? for any letter that has one.