Can I vibecode LeetCode?
NOT REALLY · don't botherAn agent can produce a Monaco editor, a problem list, a submissions table and a Judge0 sandbox in a session, and none of that is the product. LeetCode is a content and coordination asset: thousands of curated problems with hidden test cases that actually catch off-by-one and TLE, editorials, company frequency tags, and the social fact that interviewers pull questions from it, which you cannot self-host. Clone the harness and you sit staring at an empty problems directory; authoring good problems with adversarial test cases is the actual job. Build the trainer if you want a private drill rig over problems you have already seen, but do not pretend it replaces the bank.
Build a local coding interview trainer. One repo, single user, no accounts, no cloud, no telemetry. It runs on my machine.
Stack, not negotiable: Python 3.11 with FastAPI on the backend, SQLite through SQLAlchemy, a Vite + React + TypeScript frontend using the Monaco editor, Docker for code execution. Do not add auth. Do not add a hosted judge API.
Problems live on disk, not in the database. Each problem is a folder under ./problems/<slug>/ containing problem.md (the statement), meta.yaml (title, difficulty, topic tags, language stubs) and tests.json (an array of {input, expected} objects, including at least one large case for timing). Write 12 seed problems yourself covering arrays, two pointers, a stack, binary search, BFS on a grid, interval merging, and one small DP. Do not scrape or reproduce LeetCode content.
Execution: POST /api/run accepts {slug, language, code} and runs it in a throwaway Docker container. Only python:3.11-slim and node:20-slim images. Flags: --network none, --memory 256m, --cpus 0.5, --pids-limit 64, read-only root filesystem, non-root user, 5 second wall clock kill. Wrap the submitted function with a harness that feeds each test case and compares output. Return per-test pass or fail, stderr, and runtime in milliseconds. Never execute submitted code outside Docker, not even in dev mode, not even as a fallback.
Store every submission in SQLite: slug, language, code, verdict, runtime, timestamp. I want to diff my third attempt against my first.
Review queue: SM-2 style spaced repetition over solved problems. Correct solve pushes the next due date out, a failure resets it. GET /api/due feeds a Today view that tells me what to redo.
UI, three routes: problem list with difficulty, last verdict and next due date · problem view with statement left, Monaco right, Ctrl+Enter to run, results panel below · stats page with a solve calendar and per-topic pass rate.
Explicitly out of scope: contests, leaderboards, other people's solutions, discussion threads, company tags, languages beyond Python and JavaScript, mobile layout, deployment.
Ship a README with a single make dev command and a .env holding only PORT and DOCKER_HOST. Before you claim it works, prove the sandbox survives an infinite loop, a fork bomb, a 2 GB allocation, and an outbound HTTP request, and paste the output.$ open in your agent (prompt prefilled, you press enter) or copy it raw · this prompt is generated from the build plan · improve it via PR
prompt copied. want to know what dies next week?
new verdicts + top votes, weekly. free. one-click out.
Because thirty-five dollars for the month before an onsite is trivially cheap against the salary delta, and because nobody wants to author their own curriculum while also preparing for interviews. Premium buys company-filtered lists and editorials, which is a shortcut through the one resource candidates are actually short on: time. A self-hosted drill app competes on none of that. It competes on being a nicer place to redo problems you already understand, which is a real but much smaller need.
xThe problem bank itself, thousands of problems with hidden tests tuned to catch the specific ways people get it wrong
xCompany tags and frequency data, which is the main reason people pay for Premium
xEditorials and the discussion threads where the actual learning happens
xContests, ratings, and the mild public humiliation that makes you keep showing up
xAny signal that you are practicing the same questions your interviewer will ask
Nothing worth pointing at. That's why the prompt exists.
Can I vibecode LeetCode?
Not really. LeetCode's value is not the code: the moat is fifteen years of curated problems, editorials and company tags, plus everyone else practicing on the same set. See the honest breakdown above.
How much does LeetCode cost?
LeetCode costs about $35/month (Premium, checked 2026-08-16), which is $420 per year.
What do I lose by replacing LeetCode?
Honestly: The problem bank itself, thousands of problems with hidden tests tuned to catch the specific ways people get it wrong; Company tags and frequency data, which is the main reason people pay for Premium; Editorials and the discussion threads where the actual learning happens; Contests, ratings, and the mild public humiliation that makes you keep showing up; Any signal that you are practicing the same questions your interviewer will ask. If any of those are load-bearing for you, keep paying.
Is there an open-source alternative to LeetCode?
No mature open-source alternative worth pointing at, which is exactly why the one-shot prompt on this page exists.