AlphaCoder

Type HELLO and AlphaCoder shows 8-5-12-12-15, with each letter's position in the alphabet laid out underneath. Switch the format and the same text becomes A0Z25, ASCII codes, UTF-8 or binary, and every tool works in reverse for decoding. That side-by-side view is the useful part for anyone learning, because it makes clear why A can be 1 in one system and 65 in another. Results can be copied or downloaded as a text file.

The site has 18 tools in all. Classic ciphers include Caesar with an adjustable shift, ROT13, Atbash and Vigenere. There is a Morse translator, phone keypad and spreadsheet column converters, a name-to-number and word-value calculator, and gematria tools for people curious about letter-value traditions. Reference charts cover the full alphabet and a printable pigpen key.

The worksheets make it more than a converter. Each comes as a student PDF with a separate answer key: eight A1Z26 puzzles, ten Morse exercises with a reference key, and eight Caesar shift-3 messages to crack. That suits a teacher running a code-breaking lesson, an escape room designer writing clues, or a geocacher checking a puzzle cache. The about page says the converters follow published standards such as Unicode charts, standard ASCII and the ITU Morse recommendation, and that the guides draw on books like The Codebreakers and The Code Book.

Everything is free and needs no account. Conversions happen in your browser, and the privacy policy says the text you type isn't sent to AlphaCoder's servers, to Google Analytics or to AdSense. The site does carry Google AdSense ads and uses Google Analytics, which can set cookies, and it loads fonts from Google. It is built by Jack Shi, who also writes the guides and checks the worksheets.