Erudia is a free, interactive web app for learning all of mathematics — from arithmetic to graduate level — on a spaced-repetition engine that schedules reviews just before you'd forget, so what you learn stays learned.
Models the strength of every skill you have and schedules its next review for the moment just before you'd forget it — personalized to your own forgetting rate.
Estimates your level in each branch of math and uses it to pick problems at the right difficulty and to match you in duels.
A prerequisite graph of every skill; it gates lessons so you learn in the right order and computes the shortest path from where you are to any goal.
Selects each practice item to match your current ability, keeping you where challenge is close to skill.
An error classifier tags mistakes (sign, off-by-one, conceptual, and more) and gives feedback aimed at the specific misunderstanding, not a generic 'wrong'.
Moves you from fully worked examples to fill-in-the-step to independent practice as you gain competence.
Predict-before-reveal interactive lessons: you manipulate and predict, then see the result and the math update together.
Erudia's lessons are interactive, and a retention engine schedules reviews so knowledge stays — it is not a video library you watch once.
Erudia adds a spaced-repetition retention engine, full graduate-level breadth, and ranked competition.
Erudia teaches real mathematical depth to graduate level, not a gamified surface.
Erudia (erudia.org) is a free, interactive web app for learning all of mathematics, from arithmetic to graduate level, on a spaced-repetition engine that brings each idea back before it fades so it stays learned.
Yes. Adaptive placement, the full foundations track, interactive lessons, and spaced reviews are free. Premium ($7.99/month, or $63.92/year — 4 months free) unlocks every chapter through graduate level plus olympiad and competition tiers.
Dozens of subjects, from arithmetic, algebra, geometry, trigonometry, and calculus through linear algebra, real and complex analysis, abstract algebra, topology, measure theory, category theory, and competition math.
An FSRS-6 retention engine models how strong each skill is and schedules its next review for just before the idea would fade, so what you learn stays learned instead of slipping away after the test.
An FSRS-6 spaced-repetition scheduler, an Elo ability model, a knowledge-space prerequisite graph, adaptive difficulty, and a misconception-targeting error classifier.
No. A short adaptive placement check finds what you already know and starts you where it helps.
Yes. Pick a goal and Erudia gives you a direct, prerequisite-ordered path to it — foundations first, skipping what you've mastered.
Yes — ranked 1v1 math duels with an Elo leaderboard, plus global, country, and league boards.
It combines interactive lessons with a retention engine that schedules reviews so math stays learned, full graduate-level breadth, and ranked competition — not just videos or gamified drills.