A Visual Formula Editor
Write math on your cards without knowing LaTeX — the ∑ button in the card editor now opens a visual editor, on the web today and in the iOS and Android apps with their next update.
Cards in Sona have always been able to show typeset math, but writing it meant typing LaTeX by hand. Now the ∑ button in the card editor's toolbar opens a visual formula editor instead, so you can build a formula the way it looks on the page.
Build it the way it looks
Type a fraction, a square root, an exponent or a Greek letter and see it
appear as you go, or pick symbols from the on-screen math keyboard. You don't
need to know how to write something like \sqrt{\frac{a}{b}} in LaTeX. If you
do know LaTeX, you can still type it.
Edit a formula you already wrote
Put the cursor inside a formula and press ∑ again. The editor opens with that formula loaded, and confirming replaces it in place. You also choose how it sits on the card: Inline (within a sentence) or On its own line.
Nothing else changes
A formula is still saved as the same plain text it always was, so every card you've already written, and every feature that uses them, works as before: Study, every Quiz mode, Browse, decks downloaded for offline use, read-aloud and AI generation. The editor is part of the Free plan like the rest of card writing.
It's on the web now. The iOS and Android apps get it with their next update. If you're deciding what belongs on a card in the first place, How to create a useful deck is a good place to start.