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A revision app for university students, with GCSE and A-Level coming soon. Each topic is taught in a short lesson built around diagrams, many of them animated. Exam-style problems are marked mark by mark and come with worked solutions, and spaced repetition brings each topic back before you are likely to forget it.

A flashcard tests a card you already wrote. Kerfox teaches the idea first, in a lesson whose figures are simulated rather than drawn, and then asks a real exam-shaped question and marks it out of marks. The scheduling that flashcard apps are good at is here too, underneath all of it, deciding when each idea comes back.

Notes and textbooks tell you; Kerfox asks you. Each lesson builds the idea with figures that move rather than sit still, then a question marks what you write out of marks, and the solution opens 3 layers deep: the answer, the working step by step, and why the method works at all. Underneath, the memory engine decides when each idea comes back, which is the one thing a set of notes cannot do for you.

On Android, yes, for the studying itself. The lessons, the figures, the questions and the memory engine all live on your phone rather than on a server, so a tunnel, a dead signal or a plane changes nothing about a revision session, and a report you make offline is sent once you are back online. What does need a connection: signing in, backing your progress up, and the optional AI feature. The browser version, when it opens, needs a connection throughout.

No. You can walk straight through setup as a guest, every lesson and question is open to you, and a guest’s progress stays on the device: it is never copied to our servers. An account is optional and adds 2 things: a backup, so a new phone can pick up where the old one left off, and a first week with Pro switched on, with no card and nothing to cancel.

University first. Physics is the deepest shelf, from waves and light through electromagnetism to lasers and quanta, with philosophy courses beside it. GCSE and A-Level are coming soon: at A-Level, Chemistry, Biology and Maths are already written against AQA, OCR, Edexcel and WJEC, while the other A-Level subjects and GCSE are still to be written.

At A-Level, which is coming soon: AQA, OCR, Edexcel and WJEC. University has no exam board, so its lessons are written to the modules themselves. At A-Level, each lesson is written against the board’s own published specification, and a topic carries the boards it belongs to, so choosing your board changes what you are shown rather than just what it is called. Kerfox is not affiliated with any of them: naming a specification says which syllabus a lesson was written for, and nothing more.

After university, and we would rather say so here than let you find out after installing. Kerfox opens at university, where the physics and philosophy courses are furthest along. A-Level is next furthest, with Chemistry, Biology and Maths already written against all 4 boards; GCSE is a handful of starter topics so far. The waitlist hears the morning each one opens.

University is where Kerfox starts. Physics is the deepest shelf: a full module on lasers and quanta with 104 long questions, and further modules on waves and light, electromagnetism, energy and matter, and motion and relativity. There are philosophy courses as well, on logic and argument, ethics, Indian philosophy and the philosophy of mind. Several are built on first-year modules - waves, light and quanta, electricity and magnetism, reason and argument, and ethics among them - and the philosophy runs on to second-year philosophy of mind and third-year Indian philosophy. Beyond those, the module catalogue is there so you can pick the modules you are actually taking, and the lessons get written into it over time.

As many as we can, at once. The same module is taught differently at every university, so a module here is built from how several major universities teach it - Oxford, Cambridge, Imperial, UCL, Southampton, MIT, Harvard and Stanford among them - and it takes in what any of them covers, not only the part they all share. Where one university goes further than the rest, the lesson is written anyway: Waves, Light and Quanta carries 3 lessons Southampton does not teach and MIT, Cambridge and Imperial do. So whichever version you are sitting, what you are taught should be in there, alongside some things your own course may never examine. If your lecturer covers something we have missed, tell us and it goes in. Kerfox is not affiliated with any of these universities: naming one says whose syllabus a lesson was checked against, and nothing more.

Search for it and see. Every university numbers its own modules, so the same first-year electromagnetism has a different code at each one. The module catalogue in the app lists modules by name and by the university codes matched to them, so searching your module’s code or its name finds the nearest one. Lessons are written into it course by course, physics and philosophy first. Kerfox is not affiliated with any university: a code on a module says which university module it covers, and nothing more.

Probably, and telling us moves it up the list. We build subjects course by course rather than all at once, and what people are actually waiting for is what decides the order. Write to us with the subject and the level, and it goes on the list with your name against it.

Out of marks, the way a mark scheme does, rather than right or wrong. Numbers, choices and orderings are marked for you, and a number is marked on its units as well as its value, so 5 J is not accepted where 5 N was asked for. A written explanation is checked against the points a mark scheme looks for: the ones found in your answer arrive already ticked, and you confirm the rest against the model answer. The border of the answer box is cut into one arc per mark and they land one at a time, so 3 out of 4 is something you watch happen rather than a number you are handed. Common slips get named instead of shrugged at - a missing one-half, degrees where radians were wanted - and a later part is marked on the answer you actually carried forward, not on ours. At GCSE and A-Level, when they open, the marking also credits the specification’s own words, because that is what a real examiner credits, and where our marking is kinder than the board’s the solution says so out loud.

Every answer teaches it a little more about what you find hard. It brings each idea back just before it would slip, so short sessions land where they matter most.

Tell us, and thank you. There is a report control on the thing itself - a slide, a figure, a question, even a single step of a solution - so the report arrives already knowing exactly what you were looking at, and you can say what is wrong with it in a tap. You can also write to us. We would far rather hear it than leave it sitting there being wrong.

Because it has to survive the checks before you ever see it. Every course starts from its source rather than from memory: at university, the syllabus and course material of the modules it covers; at A-Level, the boards’ own published specifications. So a lesson is written against the source it claims to follow. Then every equation, answer, figure and question is run through automated checks, and a failed check fails the build rather than printing a warning nobody reads: a question whose maths does not come out, a figure whose caption overflows its frame, a marking rule that cannot tell a right answer from twice a right answer - none of those can ship. Checks catch a great deal rather than everything, which is exactly why the report control exists, and why a report gets a fix rather than a thank-you.

We are in closed testing and now taking people for the first batch release. Join the waitlist and we will write to you the morning the first release opens.

Android first, as a direct download and then on the Play Store. The full web version follows, and iOS after that.

Yes. Kerfox builds come only from us: during testing through the link we send you, and from the first public release through Google Play. If you install a build file directly, Android will ask whether you trust your browser to install apps from outside the Play Store. That prompt is about the route rather than about this file, and it is Android being sensible. If you ever meet a Kerfox APK anywhere else, it is not ours.

It is on the road, and it is the last stop on it: Android first, then the Play Store, then the full web version, then the App Store. We are not going to invent a date for something that far out. iPhones and iPads will be able to open the web version as soon as that stage lands, which is the sooner of the two, and the waitlist is told the morning each one opens.

Yes. The lessons, the questions, the marking and the memory engine are free to use. There is an optional Pro plan in the app for a few extras, and nothing you need in order to revise sits behind it.

Yes, and that is the plan rather than a launch offer: questions, marking, lessons, streaks and your plan stay free. We do not ask for card details, and a free build never turns into a charge after the fact. Kerfox Pro is the optional extra, and it is not on sale yet. When it opens it is £24.99 for 4 months, £44.99 for a year or £7.99 a month. The monthly plan renews until you cancel it; the passes are one payment and end by themselves. It adds practice made from your own notes without a monthly limit, a forecast of what you will forget before exam day, live sync across devices, and offline lessons with export. Buying it comes with its own terms, agreed before anything is charged.

Servers, store fees, and more mornings spent writing lessons. A donation buys no feature and no place in a queue: it is a gift towards the work, separate from the optional Pro plan, and it keeps the app free for the people who cannot chip in - and the kindest support, while the support page is still opening, is telling one friend who is revising.

No, and there will not be. There is no advertising code anywhere in the app, and putting adverts in front of somebody who is trying to concentrate is not a thing we will build.

This website has no analytics and no tracking pixels, and stores nothing of ours in your browser. The only cookies are two that our host, Cloudflare, sets to tell people from automated programs, and they are used for that security check and nothing else. It receives only what you choose to send it: when you press send on the waitlist signup or the contact form, what you typed is posted to our backend, which Supabase hosts and Resend delivers to our inbox, and nothing is sent while you are still typing. Our host, Cloudflare, sees requests arrive the way any web host does. The app is a separate matter and it does send things - it reports how lessons and questions went so we can see where it is failing people, an optional account keeps a backup of your progress, and a message from the app’s contact panel reaches us that way. The full account is in the privacy policy, and the app carries its own notice, published before any build asks you to install it.

You should be 13 or over to send us the signup yourself, because 13 is the age UK law sets for agreeing to something like this on your own. If you are younger, ask a parent or guardian to sign up in their own name and with their own email address, and to leave your details out of it. Kerfox is built for students, and a great many of the students it is built for are 14, 15 and 16. It is set out in the privacy policy.

Yes, and you are welcome. Use it for your own teaching, put our figures in front of a class, print what you need for your room: UK copyright already allows illustration for instruction and we are not going to narrow it. Anything wider - a website, a video, a set handed round beyond your own teaching - just ask us first, and we usually say yes. What does not exist yet is the school furniture: no class management, no dashboard, no bulk signup, so a teacher joining the waitlist signs themselves up rather than a class. Tell us what a room of 30 would actually need, because that is what decides whether we build it.

Kerfox Ltd, a company registered in England and Wales. Every equation, answer and figure passes automated checks before it ships.

No. Kerfox is the revision app at www.kerfox.app, made by Kerfox Ltd, a company registered in England and Wales. kerfox.com and Ker-Fox Photography belong to someone else, and we have no connection with them.