Trace algorithms.
Build understanding.

The study tool that works alongside your favorite curriculum. Build your own flashcards, trace through algorithms visually, drill solutions until they stick, and review with AI feedback. You decide what to study.

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Your curriculum, your pace

Most study tools give you a fixed list and a fixed order. But maybe you already know sliding window and need to focus on union find. StepThru lets you build a study plan that matches where you actually are.

Build your own decks
Add the problems that matter to you
Write your own editorials
Learning happens when you explain it
Trace your own algorithms
See what your code actually does

How it works

1
Add problems you care about
Pull from whatever curriculum you're following. Write your solution, add test cases, and write an editorial in your own words. The act of building the card is part of studying.
2
Review on a schedule
Spaced repetition surfaces problems right before you forget them. Flash cards for quick recall, drill mode to retype solutions from memory, and timed practice for interview simulation.
3
Visualize the algorithm
Build interactive traces that show how your algorithm works frame-by-frame. Step through pointers, data mutations, and state changes across 12+ data structure types.

Everything in one place

A complete study system that adapts to how you learn

Interactive Visualizations
Arrays, trees, graphs, linked lists, matrices, histograms, intervals, and more. Each frame shows pointers, highlights, regions, and annotations that explain the why, not just the what.
12+ structuresFrame-by-frameAnimated transitions
Spaced Repetition
SM-2 scheduling adapts to your recall. Problems you struggle with come back sooner. Problems you know well stretch to longer intervals. Custom decks let you group by topic or difficulty.
SM-2 algorithmCustom decksFlash cards
In-Browser Code Editor
Write and run Python right in the browser. Vim keybindings, syntax highlighting, and instant test execution powered by Pyodide.
Drill Mode
Type a solution from memory, then compare against the reference. Repeat until the implementation is automatic. Build real muscle memory.
Community & Sharing
Share editorials and visualizations publicly. Browse what others have built. Learn from different approaches.
AI Chat & Hints
Ask questions about your solution or the editorial. Get progressive hints that guide you toward the answer without spoiling it. Like having a tutor on call.
Voice Explanations
Practice explaining algorithms out loud, just like in a real interview. Record yourself walking through your approach and get AI feedback on clarity, accuracy, and completeness.

Start studying on your terms

Bring your own problems, build your own traces, review at your own pace. StepThru fits into whatever curriculum you're already following.

Get Started Free