Noji – Flashcards study app

Review by eFreeware

The feature that stands out in Noji is image occlusion: you hide the labels on a diagram, try to recall each one, and reveal the answer only after you have made an attempt. That is a different exercise from flipping a term-and-definition card, and it is the reason this app caught my attention. The developer positions it around anatomy diagrams, biology cells and lab practicals, along with test prep for the SAT, GRE, AP, MCAT and USMLE.

Noji comes from DelightHub and sits in the Education category. It is free to install, carries no ads, and offers in-app purchases. The install base is substantial, over a million, with a 4.1 average across roughly 26,900 ratings. It has been on Google Play since January 2022, and the most recent update is a round of bug fixes and stability improvements.

The app is pitched as a companion to whatever study tools a student already keeps open, rather than a replacement for them. If your routine already involves flashcards, notes or homework help from other services, the idea is to pull the important pieces into Noji and drill them there. That framing tells you a fair amount about who will get value from it: someone preparing for a content-heavy exam who wants recall practice rather than another place to read.

Image occlusion for diagrams and labeled figures

Image occlusion works the way you would want it to. You take an image, cover the labels you need to know, and work through them one at a time. The guess comes before the reveal, which is the part that matters for memory. The developer lists anatomy diagrams, biology cells, maps, formulas, screenshots and textbook images as fair game, and I can see the appeal for anyone staring at a chart and hoping it sticks.

This is the feature I would build a study session around if I were preparing for a lab practical or a diagram-heavy section of the MCAT or USMLE. Staring at an already-labeled figure is passive; covering the labels forces you to produce the answer yourself. For AP Biology or a final exam with a lot of visual material, the same logic applies.

What I appreciate is that the app does not treat image occlusion as a side feature. It is described as one of Noji's strongest capabilities, and the use cases listed are specific rather than generic. If your exam leans on recognizing structures and their names, this is the part of the app to try first.

Spaced repetition with four review grades

Reviews in Noji are graded on a four-point scale: Again, Hard, Good and Easy. Easy cards move further out, Hard cards come back sooner, Again cards return quickly, and Good cards stay on their normal track. That is a familiar model for anyone who has used a spaced repetition system, and the developer's pitch is a simpler flow around it.

The reasoning behind the four grades is sound. You spend your review time on the cards you keep missing and less on the ones you already know. The developer frames this as fixing the parts that cost points, which is a reasonable way to describe what spaced repetition is for. Whether the scheduling feels right in practice is the kind of thing each student judges for themselves.

Where the app competes is on simplicity rather than depth. The interface is kept plain so the focus stays on memory. If you have found other spaced repetition tools fiddly, the promise of a lighter flow is the draw here. It suits learners who want a simple routine built around spaced repetition.

Building decks once and reviewing them anywhere

Decks sync across devices, so you can create on a PC or tablet and review on a phone. The developer gives a concrete example: build a deck from a PDF on a computer, add image occlusion cards on a tablet, then run through them on your phone. For a student who studies at a desk and reviews in spare moments, that division of labor makes sense.

There is also a customization layer. You can adjust fonts, templates and text size to shape how your cards look. That is a small thing until you are reading hundreds of cards a day, at which point legibility and a layout you like stop being cosmetic.

For vocabulary work, the developer suggests generating a CSV of hard English words for the SAT or GRE and importing it to build a deck quickly. The app can play English word pronunciation while you review, which is a useful addition for words you recognize on the page but have never heard spoken. Neither of these is a headline feature, but together they cover the mechanics of getting material in and hearing it back.

Getting material into Noji

You can build decks on a PC or tablet, import a CSV to create a deck, and start from a PDF on a computer. The app is framed as a place to consolidate material you have gathered elsewhere, so the practical starting point is whatever you already have in front of you.

For vocabulary decks, the suggested route is to make a CSV of the words you need and copy it in. That is a low-friction path if you already have a word list. For diagram work, you would bring in an image and start hiding labels.

Noji is free with in-app purchases available, and it shows no ads.

Students who will get the most from it

The clearest fit is a student in a content-heavy program where diagrams and terminology carry real weight. Anatomy, biology, lab practicals and the science sections of the MCAT or USMLE all reward the kind of recall practice Noji is built around. The image occlusion tool is the reason to pick this app over a plain card flipper.

The second fit is a test taker working on vocabulary or facts for the SAT, GRE or AP exams. The CSV import and pronunciation playback make short work of building a word deck, and spaced repetition handles the rest. A student who already keeps notes or flashcard sets in other services can use Noji as the place where the important pieces get drilled.

The app is also pitched at people who want a lighter review flow than a full spaced repetition system offers. If the four-grade model and a simple interface sound like the right balance, that is the trade Noji is making. The 4.1 average across a large number of ratings suggests the approach lands with most people who try it, though as always that is an average and not a promise.

The case for making Noji your drill app

Noji is worth installing if image occlusion is the feature you have been missing. Hiding labels, guessing, then revealing is a genuinely different exercise from reading a labeled diagram, and the app is built around that idea rather than treating it as an afterthought. Add spaced repetition with four grades and sync across devices, and you have a complete loop for exam prep.

The app is free, shows no ads, and offers in-app purchases. The install base is large and the rating solid, and the developer is still shipping updates. For a student in anatomy, biology or a diagram-heavy exam track, that combination is easy to justify trying.

If your study material is mostly text and you already have a system you like, the appeal here is narrower. But for anyone who has ever looked at a chart the night before a practical and wished they had tested themselves properly, Noji is aimed at exactly that problem.

What's new in version 26.36.1

Various bug fixes and stability improvements.