Arabic → Arabizi.
Turn Arabic script into the chat alphabet, the way people actually type it in WhatsApp and Instagram comments. مرحبا becomes mar7aba, and the sounds English can't spell get their numbers: حبيبي comes out 7abibi. Paste a word or a whole message.
Paste Arabic, get Arabizi.
Run it through the Arabizi translator and you get Arabic script back, with the full mapping chart under it.
Ten sounds get numbers. The rest map straight across.
Most Arabic letters have an obvious Latin twin: ب is b, ش is sh. The ten that don't are the throat and emphatic sounds, and chat writes those with the digits that look like them — ح→7, ع→3, خ→5, ط→6, ق→8, ص→9, ء→2, plus the apostrophe variants 3', 6', 9' for the dotted letters. Prefer plain letters? Flip the converter to its letters style and you get kh, gh, q and friends instead.
Shadda doubles the letter (يلّا → yalla), and ta marbuta comes out as a plain a (ساعة → sa3a). Bare script hides its short vowels too, so the converter fills in an awherever Arabic syllable rules demand one; that's why مرحبا reads mar7aba, not mr7ba.
Want the full letter-by-letter chart? It lives on the Arabizi → Arabic page, and the story behind each digit is on the numbers guide.
The numbers look like the letters.
Put the shapes side by side and the whole trick clicks. Seven digits cover the sounds English can't quite spell; three take an apostrophe for the dotted letters below.
The apostrophe means “add the dot.”
Once you know ع → 3 and that غ is ع with a dot, then 3' → غ makes sense without memorizing anything new.