T9 / Phone Keypad (Multitap)
Encode and decode text using the multitap method of the classic phone keypad — the way you typed SMS on a numeric keypad before smartphones. Each letter lives on a digit key (2=ABC, 3=DEF, 4=GHI, 5=JKL, 6=MNO, 7=PQRS, 8=TUV, 9=WXYZ), and you press the key once for the first letter, twice for the second, three times for the third (and four times for S, Z, and the four-letter keys). So A=2, B=22, C=222, S=7777, SPACE=0. Encode text to a space-separated sequence of digit presses and decode it back, with the full keypad shown for reference. Everything runs locally in your browser.
Encode (text → key presses)
Decode (key presses → text)
Keypad reference
The math. The classic phone keypad assigns three or four letters to each digit 2–9: 2→ABC, 3→DEF, 4→GHI, 5→JKL, 6→MNO, 7→PQRS, 8→TUV, 9→WXYZ (the 7 and 9 keys carry four letters because the 26-letter alphabet doesn't divide evenly by eight). In multitap entry a letter is entered by pressing its key a number of times equal to its position on that key (1 for the first, 2 for the second, 3 for the third, 4 for the fourth), so E (2nd on 3)=33 and S (4th on 7)=7777. The digit 0 is the space. Because two consecutive letters often share a key (e.g. AB both on 2), the encoded groups are separated by spaces so the decoder can split them unambiguously — AB encodes as 2 22, not 222 (which is C). Encoding handles only A–Z and spaces (digits, punctuation, and lowercase are normalized or ignored); decoding treats each whitespace-separated token as one letter's key-presses and marks any token that isn't a single repeated digit 2–9 (or 0 for space) with a ?. Pairs with the Tap Code, Morse Code, and NATO Phonetic alphabet tools. Everything runs locally — nothing leaves your browser.