Spaced repetition for developers
Practice coding.Remember what you learn.
Solve programming problems in your browser, check your code against tests, and revisit what you learn with spaced repetition.
No account or credit card needed to try a free topic.
Start with Modern C++.
C++ · Python · Rust · TypeScript · Zig
Animated demo: MemPro types a two-sum solution in Rust, a test fails because the value is inserted before the complement check, a hint explains the bug, the line moves below the check, tests pass, and the card is scheduled for another review.
1 · Recall
Find the indices of two numbers that add up to target in O(n) with a HashMap.
no test output yet
How well did you recall it?
recall → attempt → test → schedule
01
Try it from memory
Answer a question or write a solution. Hints are there when you need them.
02
Check your understanding
Run your code against tests, then compare with the reference solution.
03
Review it later
Rate how well you remembered it. MemPro schedules your next review.
01 / Topics
What do you want to get better at?
Prepare for an interview, practice a new language, or work through a concept like concurrency. Open a topic to see its questions and exercises.
Modern C++
Hands-on modern C++ (C++11 through C++17): value categories and move semantics, perfect forwarding, RAII and smart pointers, user-defined literals and constexpr, tuples and the vocabulary types, chrono, random, and regex. Every card is a small exercise with tests, or a multiple-choice check on the idea behind it.
#cpp #modern-cpp #c++11
Preview topicRust Through Problem Solving
Learn Rust by solving engaging computer science problems and interview questions. Master ownership, iterators, and idiomatic Rust naturally through hands-on challenges.
#rust #problem-solving #interviews
Preview topicC++ Templates: Deduction to Concepts
Master C++ templates from deduction and specialization through SFINAE, concepts, and senior-level template design. Each deck pairs focused mechanics with the prediction, repair, and implementation questions interviewers actually ask.
#cpp #templates #metaprogramming
Preview topic02 / Spaced repetition
Know what to practice next.
Your recall rating sets each card's next review. Practice what is due instead of deciding what to revisit yourself.
Still learning it?
Score it Again to review it sooner. Use the next attempt to work through what you missed.
Remembering it well?
As you keep recalling a card successfully, the gaps between reviews grow. Spend more of your practice on material that needs attention.
See an example review schedule
For a new card rated Good at every review, the default schedule below shows how the intervals grow. Your dates depend on your ratings and review history.
- 013 days
- 0214 days
- 0357 days
- 04196 days
- 05586 days
03 / Pricing
Start free. Upgrade for the full library.
Free topics include coding exercises and scheduled reviews. Pro opens every premium topic. Author adds an editor for writing your own.
Free
Start practicing with the free collection.
- Every free topic
- Coding exercises with test results
- Scheduled reviews and progress tracking
Pro
Or $90/year. Cancel anytime.
- Everything in Free
- Every premium topic
- Higher daily code-run limits and priority grading
Author
Or $150/year. Cancel anytime.
- Everything in Pro
- Write your own topics, decks, and cards
- Runnable code exercises in five languages
- MCP server for Claude Code and Cursor
14-day goodwill refund window on Pro and Author · cancel anytime
04 / FAQ
Questions, answered
The practical details before you begin.
Do I need an account to try it?
No. You can browse free topics, practice cards, and run code without an account. Sign in with Google to keep your progress across devices. No payment is needed to practice free topics.
What does a practice session look like?
Each card asks you to explain a concept or solve a coding problem. Try it from memory, use a hint if you need one, and check your answer. For code exercises, run your solution against tests in the browser. Then rate your recall to schedule the next review.
Which programming languages can I practice?
Code exercises support C++, Python, Rust, TypeScript, and Zig. Available languages depend on the topic. You can also practice algorithms, concurrency, design patterns, and interview concepts.
Is code grading available on the free plan?
Yes. Free topics include code exercises with test results and scheduled reviews. Daily code-run limits apply. Pro unlocks every premium topic and gives you higher daily limits.
Can I cancel Pro at any time?
Yes. You can cancel through the billing portal. Your Pro access continues until the end of the current billing period.
Get started
Start with one free topic.
Pick a question, try a solution, and see how the practice feels. Sign in whenever you want to keep your progress across devices.