spaced repetition apps: which ones actually help with long-term retention?

Anki is the gold standard for a reason. It's free on desktop and Android, the spaced repetition algorithm is well-tested and highly configurable, and the community shared-deck ecosystem is massive. For pharmacology specifically, there are pre-made decks with thousands of cards covering drug classes, mechanisms of action, side effects, and interactions. You'd spend weeks creating those cards from scratch.

The learning curve is steeper than other apps because the interface is dated and customization options are overwhelming at first. But that flexibility is exactly what makes it powerful. You can adjust intervals, create custom card types with cloze deletions and image occlusion, and sync across devices seamlessly.

My one criticism: Anki's default settings are too aggressive for most students. The initial interval is one day and the graduating interval is only four days, which means you're reviewing new cards very frequently early on and the workload stacks up fast. I'd recommend changing the graduating interval to seven days and the easy interval to four days. That reduces the early review burden without sacrificing long-term retention.

I used RemNote for two semesters before switching to Anki and I'd say they serve slightly different purposes. RemNote is better if you want your notes and flashcards integrated into one system. You can create cards directly from your lecture notes with a single keystroke, which saves time and keeps everything connected. The spaced repetition algorithm is decent, not as mature as Anki's SM-2 implementation but perfectly functional for most use cases.

The downside is that RemNote's free tier has limitations on the number of flashcards and some features are paywalled. The paid plan is not cheap for a student on a budget. Also, I found it slightly less reliable for very large card volumes. Once I had over 2000 cards the review sessions started feeling sluggish and loading times increased noticeably. Anki handles tens of thousands of cards without any performance issues because it runs locally rather than in the browser.

That said, if you value the convenience of notes and flashcards in one place over raw algorithm power, RemNote is worth trying on the free tier first.

I've used both Anki and RemNote extensively, plus I briefly tried Mochi, so here's my detailed comparison for someone in a memorization-heavy course like pharmacology.

Anki wins on algorithm maturity, customization, and community resources. The SM-2 algorithm it uses has decades of research behind it, and the AnKing community (which grew out of medical school use cases) has optimized settings specifically for health sciences. For pharmacology, I'd look up the AnKing Step deck or similar medical science decks as a starting point and then customize from there. Making your own cards is ideal for learning, but supplementing with pre-made decks saves enormous time when the volume is as high as pharma requires.

RemNote wins on user experience and note integration. If you're someone who takes notes digitally and wants a single tool for everything, RemNote's approach of turning notes directly into flashcards is genuinely convenient. The UI is also much more modern and intuitive than Anki's, which still looks like it was designed in 2005.

Mochi is worth mentioning as a middle ground. It has a cleaner interface than Anki with Markdown support, the algorithm is solid, and the free tier is generous. But it lacks the community decks that make Anki so powerful for medical and science courses.

For your specific use case, pharmacology with high card volume, I'd recommend Anki. The community decks alone will save you dozens of hours, and the algorithm handles large volumes better than anything else. Spend an hour watching a setup tutorial, install the recommended add-ons (Image Occlusion Enhanced, Review Heatmap, and the AnKing note type), and you'll be set.

One critical tip regardless of which app you choose: do your reviews every single day, no exceptions. The entire benefit of spaced repetition depends on consistency. Skipping three days creates a review backlog that's demoralizing and undermines the spacing effect. Even 15 minutes a day is enough if you stay consistent.

Another vote for Anki. The daily consistency point from @ethan_w is everything. I missed a week once and came back to 400 overdue cards. Took me three days just to clear the backlog and it was genuinely demoralizing. Never again. Set a recurring alarm and do your reviews before anything else each morning.

Used Anki all through undergrad for biology courses and it genuinely carried my grades during exam season. The upfront time investment in making good cards pays for itself ten times over when you're reviewing before finals. One thing I'd add: make cards that test understanding, not just recall. Instead of "What is the mechanism of action of metformin?" try "A patient with type 2 diabetes presents with lactic acidosis. Which drug is most likely responsible and why?" Scenario-based cards are harder to make but way more effective for clinical application and they prepare you better for exam questions that test application rather than memorization.