Machine Coding
Code in the editor. Ship under pressure.
100+ JavaScript and React machine coding challenges—in-browser editor, automated tests, company tags, optional EvalPro feedback, and a profile progress dashboard when you sign up.
Free challenges · Profile progress dashboard · EvalPro when signed in
Who it's for
Machine coding, JavaScript to React
One catalog for UI coding rounds—start with vanilla JS widgets, switch to React components, or filter by the company tags your loop mentions.
- Frontend engineer interviews
- Machine coding rounds
- JavaScript UI loops
- React component building
- FAANG machine coding prep
- Full-stack frontend panels
Three pillars
What you'll master
Editor-first practice—real machine coding patterns, filters that match how you prep, and EvalPro when you want structured feedback on your submission.
Live in-browser coding
Write, run, and preview—same constraints as a real machine coding loop
- JavaScript and React sandboxes with starters
- Run automated tests on your submission
- Preview UI output without leaving the tab
- Timer and progress tracking when signed in
Real interview patterns
Problems shaped like UI rounds—not abstract puzzles disconnected from frontend work
- Components, DOM manipulation & async flows
- Filter by category, difficulty & company tag
- Keyword search across the full catalog
- 70+ JS and 30+ React challenges
Interview-ready outcomes
Drill under time pressure, then validate with EvalPro when you want a second opinion
- Mark challenges solved on your account
- Profile dashboard with solved vs remaining stats
- Difficulty breakdown and per-track charts
- Solved list with links back to each problem
Every stack covered
Two tracks in the catalog—open Explore to filter by category, difficulty, and company tags.
| # | Stack | What you'll build |
|---|---|---|
| 1 | JavaScript | DOM widgets, utilities, async flows, arrays & objects—vanilla JS in a live sandbox with tests. |
| 2 | React | Components, hooks, lists, forms & UI state—React machine coding with in-editor preview. |
Explore & review
Browse the catalog, track solved work on your profile dashboard, and pair practice with EvalPro or DSA lists.
Progress dashboard
LeetCode-style tracking on your profile at `/user/your-username`—solved gauge, difficulty charts, and JS, React, and DSA stats as you mark problems complete.
- Solved vs remaining at a glance
- Easy, Medium, Hard breakdown
- Per-track progress bars and solved list
EvalPro AI Agent
AI-powered codejudge on your editor submission—fresh test angles, sandbox runs, and feedback on logic and trade-offs.
- Dynamic evaluation on practice code
- Structured feedback—not just pass/fail
- Uses your signed-in EvalPro quota
DSA by Patterns
260+ curated DSA problems by topic and pattern—LeetCode links and company tags when you need algorithm depth alongside UI rounds.
- Topic-wise lists with pattern labels
- Arrays, trees, graphs, DP & more
- Complements machine coding prep
Ready to code?
Open the catalog, pick a stack, and launch a challenge in the live editor.