AnkiMobile is the most capable spaced-repetition app on iOS. Heddy is a tutoring app with a deliberately simple one. The comparison is really about how much work you are willing to do before any studying happens.
At a glance
| AnkiMobile | Heddy | |
|---|---|---|
| Cost | One-off paid app on iOS (free elsewhere) | Free |
| Who writes the cards | You, every one | The tutor, from your lesson |
| Algorithm | SM-2 default, FSRS available | SM-2, fixed constants |
| Maximum interval | 100 years by default | 90 days |
| Daily limit | Configurable (200 default) | 20, fixed |
| Can a card be finished? | No | Yes — mastered |
| Offline | Fully | Cards yes, tutors no |
| Customisation | Effectively unlimited | None |
| Someone to explain a card | No | Yes — eight tutors |
| Best for | A self-directed adult | A student who wants teaching |
What Anki does better, and it's a lot
The scheduler, especially with FSRS. Anki's optional modern scheduler models each card individually rather than applying fixed multipliers, and gets roughly the same retention from meaningfully fewer reviews. It's a real improvement on SM-2, and we're still on SM-2 — honestly, because we don't yet have enough review history to train anything better.
It's yours, permanently. Open source, a local collection file, no subscription and no company that can change the terms. For a learner thinking in decades, that matters enormously.
It works fully offline. Ours reviews offline but the tutors need a connection.
It scales to tens of thousands of cards and every kind of customisation you can describe. Ours is built for a child's school years and offers no settings at all.
If you are a self-directed learner who will still be reviewing this collection in ten years, use Anki. That's not politeness; it's the correct recommendation.
Where it fails a fourteen-year-old
Not in the algorithm. In everything around it.
Card-writing is the wall. Anki requires you to write every card, and writing good cards is a genuine skill — one fact per card, unambiguous prompts, no cards that test two things at once. This has to happen at the end of studying, when you're finished and want to stop. It is where the overwhelming majority of teenage Anki attempts end, and no amount of scheduling quality rescues a collection that was never made.
Heddy inverts it: the professor who just taught you types the deck. /cards, four seconds, filed under the right subject, with the error you actually made recorded on it.
A hundred-year interval is wrong for a schoolchild. Anki's default maximum means a well-known card effectively never returns — sensible for a career, wrong for someone with an assessment in April. Ours caps at 90 days: everything comes back within a term.
A backlog you can't clear is fatal. Anki's configurable daily limit is a gift to an adult and a trap for a child, who will set it high in week one and face 340 due cards by week three. Ours is fixed at twenty, deliberately not adjustable.
And nobody explains anything. Four Agains on the same card is a teaching problem, and Anki has no teacher. Heddy lets you carry that exact card into the subject tutor's room with the question already asked — the gesture the whole app exists for.
The honest summary
Anki is a better spaced-repetition system than ours and will remain one. It is also a tool that assumes an autonomous, motivated adult who enjoys configuring things — and if you are that person, the comparison ends here in Anki's favour.
Heddy assumes a tired fifteen-year-old with homework, no interest in deck options, and nobody to ask at nine in the evening. Different user, different product, and the second one is why we didn't just tell everyone to install Anki.
Comparison written 10 Sep 2026 from each product's public documentation. Features and pricing change — check the current App Store listing before deciding. Written by Duke Harewood, who builds the tutors at aitutors.me.