Which spaced repetition app should you actually use?

An honest map of the spaced repetition app landscape from someone who ships one. Anki is still the default answer, but the right app depends on where your cards come from and when you review. Picks by use case, the failure mode each app has, and who should skip each one.

Disclosure first: I ship a spaced repetition app, so I have an interest in this question. I am also going to tell you that most people asking it should just use Anki, which is not my app. What follows is the map I wish someone had handed me before I built in this space: the real options, what each one is actually good at, and the specific way each one fails, because every SRS app has a failure mode and the reviews never mention them.

The short version: the right app is decided by two questions. Where do your cards come from, and when will you actually review. Algorithms matter far less than either; every serious app implements spacing well enough. Match the app to your card source and your review slot and it will stick. Mismatch either one and you will quit within a month regardless of how good the scheduler is.

Anki: the default, and correctly so

Anki is free and open source on desktop and Android, with a paid iOS app that funds the project. Twenty years of shared decks, a plugin for everything, and a modern scheduler (FSRS) built in. If your cards come from anywhere (medical school, languages, trivia, code), Anki can hold them, and no other app matches its ceiling for power users.

The failure mode: Anki assumes you will show up daily, and its due counter turns missed days into visible debt. Skip a bad sprint week and it greets you with hundreds of cards owed. Disciplined daily reviewers never see this problem; everyone else eventually does, and we wrote a whole post about why developers in particular quit Anki and the settings that soften it if you stay.

Skip it if: your schedule has high variance and you know yourself. The debt spiral is not a settings problem at heart, it is a contract problem.

RemNote: cards that come from notes

If your cards originate in lecture notes or reading notes, the copy-paste hop from notes app to flashcard app is where the habit dies. RemNote's bet is merging the two: it is a note-taking app where any line can become a card in place. Students with heavy note volume are the natural fit, and for them the integration genuinely removes the biggest friction in the pipeline.

The failure mode: it is a workspace, not a utility, and it wants to be where your knowledge lives. If you already have a notes system you like, adopting RemNote means migrating your notes or maintaining two systems, and the second one always rots.

Skip it if: your notes live happily elsewhere, or you want a tool rather than a home.

Mochi: markdown cards for people who live in editors

Mochi is flashcards as markdown: cards are plain text with a delimiter, decks feel like documents, and the whole thing respects keyboard-first, plain-text workflows. For developers who want to write cards the way they write everything else, it is the lowest-friction authoring experience in the category.

The failure mode: the ecosystem is thin compared to Anki. Fewer shared decks, fewer integrations, fewer escape hatches when you want something exotic.

Skip it if: you want premade decks or heavy customization.

SuperMemo: the origin, for the devoted

SuperMemo invented this field, and its incremental reading feature (turning long articles into a scheduled reading and extraction pipeline) still has no real equal. It is also Windows-centric software with a famously steep learning curve and an interface that has not chased modern polish.

Skip it if: you are not prepared to treat learning the tool as a hobby in itself. Most people should read about incremental reading and then use something else.

Quizlet and Brainscape: the classroom lane

Both are built for course-shaped studying: premade sets, classes, sharing with a cohort. Quizlet is the biggest library of premade material anywhere, but classic free-form spaced repetition is not its center of gravity, and the experience is tuned for cram cycles as much as retention. Brainscape runs on confidence-based repetition, a legitimate cousin of SRS, with a curated library.

Skip them if: you are building a personal long-term retention practice rather than passing a specific course. The course-shaped tools optimize for the exam date, and spacing's whole value is what happens after it.

Unwait: the one we make, for time you already lose

Unwait is not a general-purpose SRS, and if you want one, pick from the apps above. It does one narrow thing: if you work with AI coding agents, you wait dozens of times a day, thirty seconds to a few minutes per turn, and Unwait shows exactly one flashcard in that gap on your Mac, then gets out of the way when your agent needs you. No due counter, no session quota, no separate review time slot; the schedule is a fixed ladder that tolerates irregular days because agent waits are irregular by nature. It is $1.99 a month or $19 a year with a 14-day trial, macOS only.

The failure mode, stated plainly: no agent waits, no reviews. If you do not spend your day alongside Claude Code, Codex, or similar, Unwait has no slot to live in, and one card per wait means it optimizes for a steady drip over deep study sessions. Medical students should be in Anki.

Pick it if: the review time you keep failing to schedule is the whole problem, and your day is already full of thirty-second holes.

How to actually decide

1. Find your card source. Notes-heavy: RemNote. Plain-text authoring: Mochi. Premade decks or anything goes: Anki. Course with an exam date: Quizlet or Brainscape.
2. Find your review slot before you commit. A daily ritual you already keep (commute, coffee): Anki thrives there. No reliable slot and an agent-heavy workday: that is the gap Unwait was built for. No slot and no dead time: fix that before choosing software, because no scheduler survives having no time to run in.
3. Start embarrassingly small. Twenty cards, two weeks, whatever app you picked. Every SRS failure story starts with a weekend spent building four hundred cards. The tool was rarely the problem; the opening bet was.

The honest summary: Anki if you will show up daily, RemNote if cards come from notes, Mochi if you think in markdown, and ours if the showing up is exactly what keeps failing and your terminal already makes you wait all day.