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A gamified study companion from GCSE to PhD: lessons that move, questions that bite back, and a fox who keeps count.

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.

Yes, for the studying itself. The lessons, the figures, the questions and the memory engine all live on your device rather than on a server, so a tunnel, a dead signal or a plane changes nothing about a revision session. What does need a connection: signing in, backing your progress up, sending us a report, and the optional AI feature.

No. You can walk straight through setup as a guest and nothing is held back, because your progress is kept on your own device rather than in our records. An account is optional and adds one thing: a backup, so a new phone can pick up where the old one left off.

GCSE to PhD. A-Level Chemistry, Biology and Maths are complete across AQA, OCR, Edexcel and WJEC, and the university shelf begins with a full physics module on lasers and quanta. More is growing.

At A-Level: AQA, OCR, Edexcel and WJEC. 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.

Less than we would like, and we would rather say so here than let you find out after installing. GCSE is a handful of starter topics at the moment. The finished courses are at A-Level, where Chemistry, Biology and Maths are complete across all four boards, and GCSE is what the same machinery gets pointed at next. The waitlist hears when it lands.

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. 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.

Probably, and telling us moves it up the list. Kerfox is written by one person, so subjects arrive one course at a time 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. The border of the answer box is cut into one arc per mark and they land one at a time, so three out of four is something you watch happen rather than a number you are handed. At GCSE and A-Level the marking 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. 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.

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. The research phase reads the boards’ own published specifications rather than working from memory, 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, with one honest note about how Android words its warning. The file comes from our own releases page, which is the only place we publish builds, and 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. Kerfox is free to use, and the core of it, lessons, questions and the memory engine, is meant to stay free.

The heart of it is meant to, and that is the plan rather than a launch offer: the lessons, the questions and the memory engine stay free. We do not ask for card details, and a free build never turns into a charge after the fact. The app does already show a Pro page with prices on it, and nothing there can be bought - no purchase path is connected, the prices are placeholders, and the only limit Pro would lift today is on the optional AI feature. If a paid tier ever opens it will be its own separate choice, with its own price and its own terms, agreed before anything is charged.

Servers, store fees, and more mornings spent writing lessons. Supporting Kerfox buys no feature, no tier and no place in a queue, because the whole point of it is that the app stays 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. There are none today, 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 want to build. If that ever changed it would be a change we announced, not one you discovered.

This website collects nothing. It sets no cookies, it has no analytics and no tracking pixels, it stores nothing in your browser, and the signup has no server behind it at all: it composes an email in your own mail app, and nothing reaches us until you press send yourself. 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 the message. 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 thirty would actually need, because that is what decides whether we build it.

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