Best Organic Chemistry Apps: An Honest Comparison

Organic chemistry is the course where students first discover that reading harder does not work. The subject rewards two things — pattern recognition and repeated retrieval — and the apps that help are the ones that force you to do something rather than look at something. That is the lens we used here.

Below are five well-known organic chemistry apps, compared against each other and against the app we build. Everything was checked against each app's own store listing or website in August 2026, and the sources are listed at the bottom. We have deliberately left out star ratings and download counts: they change weekly and tell you nothing about whether an app fits your syllabus.

How did we compare them?

Four practical questions:

• Platforms. Study groups are mixed. An iOS-only tool is fine for you and useless for your lab partner on Android.
• Price model. Free, one-time purchase, or subscription — each is legitimate, but you should know which one you are signing up for before exam season.
• Works offline. Libraries, trains, basements. We only mark “yes” where the maker states it, which is rarer in this category than you would expect.
• Account required. Some study tools are genuinely better with an account (sync, instructor assignments); some just want your email.

Where a listing does not address a point, the table says not stated. That is not a “no” — it means we could not verify it, and we would rather show a gap than invent a fact. That applies to our own app too.

The comparison at a glance

ReactionFlash — the serious named-reaction reference

ReactionFlash is published by Elsevier and was designed in consultation with Professor Dr. Erick M. Carreira of ETH Zürich. It covers 1,266 named reactions, which its makers describe as by far the largest such collection, and every card carries the reaction, its mechanism, and examples drawn from peer-reviewed published literature. There is a quiz mode, and the app links into Reaxys for recent examples with experimental detail.

It is free on iPhone, iPad and Android, and the Google Play listing shows no ads and no in-app purchases. For anyone past second-semester orgo — a synthesis student, a graduate researcher, someone preparing for a group meeting — this is the strongest reference in the list, and we would recommend it over our own app for that use. Its scope is also its limitation: 1,266 named reactions is a firehose if you are trying to survive a first-year exam on twenty of them.

Organic Reaction Cards — flashcards built by a chemistry professor

Aaron M. Hartel's app does one thing extremely well: it turns reactions into configurable flashcards. You build a deck from the topics your class actually covers, then choose which component to hide — reactant, reagent, or product — and flip to reveal it. Hiding the product drills forward prediction; hiding the reagent drills synthetic thinking, which is the skill most exams reward and most students never practise. The reaction name can be hidden separately.

The free app covers over 40 reactions across electrophilic addition to alkenes, dienes, electrophilic aromatic substitution, and reactions of substituted benzenes, with notes on stereoselectivity, regioselectivity and limitations; additional cards covering over 150 common reactions can be purchased. You can also delete reactions your course does not cover, which sounds trivial and is not — pruning a deck to your syllabus is the single highest-value thing you can do with any flashcard tool. It is iPhone and iPad only.

Mechanisms by Alchemie — the one that makes you push electrons

Mechanisms is the most pedagogically distinctive app here. Instead of reading a curly-arrow diagram, you drag electrons yourself to form and break bonds, and the app tells you immediately whether the move works — with textual feedback explaining common mistakes when it does not. It runs in a web browser and on iPhone and iPad.

The free tier gives you 50 puzzles spread across the Intro, Structure, Acid-Base, Addition and Carbonyls packs; Alchemie states that the remaining 215 puzzles unlock for a one-time purchase of $9.99. If your specific failure mode is “I can follow a mechanism when I read it but I cannot generate one,” this is the app to try first, and the free 50 puzzles may be enough on their own. It is a practice tool, not a reference — it will not tell you what DIBAL-H does.

Chemistry By Design — real syntheses as flashcards

Chemistry By Design comes out of Professor Njardarson's group at the University of Arizona, with support from the university's Office of Instruction and Assessment and the National Science Foundation. It is a growing database of natural product and pharmaceutical syntheses presented as interactive flashcards: for each step in a real published route, you are shown some of the starting material, reagents and product, and asked to supply the rest.

It is free, available on iPhone, iPad and Android as well as on the web, and it is the only tool in this list that puts you inside actual literature syntheses rather than textbook exercises. For an advanced undergraduate or a synthesis-track student, browsing a few routes a week is an unusually efficient way to build reagent intuition. It assumes you already know the basics, so it is the wrong starting point in week three of the course.

Anki — not an orgo app, and often the right answer anyway

Anki is a general spaced-repetition system, free on Windows, macOS, Linux and Android, with the iOS app AnkiMobile sold as a $24.99 one-time purchase that funds the project. The optional AnkiWeb service syncs cards across devices; you only need an account for that.

We are including it because it is honest to: for MCAT and DAT candidates especially, a well-maintained orgo deck reviewed daily in Anki tends to outperform any purpose-built app, ours included, on the thing that actually decides exam scores — long-term retention. The trade-offs are real. Anki has a steep first week, the card quality is entirely on you or on whoever made the shared deck, and the iOS price is the highest in this comparison. But if you have a working Anki habit, adding another app is probably not your bottleneck.

Octet — ours, and where it fits

Full disclosure: we make this one. Treat this section as the developer's own account, not an independent review.

We built Octet as a pocket reference for the middle of the course, where most students actually live. It carries 80+ essential reactions — substitution (SN1, SN2), elimination (E1, E2), electrophilic aromatic substitution, Grignard reactions, aldol condensations and more — each with a step-by-step mechanism breakdown, reagents and conditions, and stereochemistry and regiochemistry notes. Alongside them sit 25 functional group cards with IR and NMR signatures, a database of 60+ reagents organised by what they do (oxidising, reducing, nucleophiles, protecting groups), and quick-reference pKa, IR frequency, and NMR shift tables. Flashcard Mode lets you mark reactions “know” or “learning”; Comparison Mode puts two reactions side by side. There are no accounts or sign-ups, search is fuzzy and fast, and there are light and dark themes. The free tier is 20 reactions, 8 functional groups and 15 reagents; Premium unlocks the rest plus flashcards, comparison mode and bookmarks.

Where we would not recommend it: we do not claim offline operation, so if that matters to you, verify it before you rely on it. We are iPhone and iPad only — Android users should look at ReactionFlash or Chemistry By Design. We have no practice-problem engine, so Mechanisms is the better electron-pushing trainer. And we cover 80+ reactions, not 1,266; past undergraduate orgo, ReactionFlash is the deeper reference.

Which one should you actually install?

• You cannot generate mechanisms: Mechanisms by Alchemie (start with the free 50 puzzles).
• You need a deep, credible named-reaction reference: ReactionFlash.
• You want to drill reactions on your own syllabus: Organic Reaction Cards.
• You are past the basics and want real synthetic routes: Chemistry By Design.
• Your problem is forgetting, not understanding: Anki.
• You want one iPhone reference for reactions, functional groups and reagents with no sign-up: ours.

A realistic setup for most undergraduates is two apps, not five: one reference you trust and one thing that makes you retrieve. Adding a third rarely helps.