Levelup Practice · Prep · Build
Runs entirely in your browser — nothing to install

Level up your
frontend career.

Hands-on labs for JavaScript, React and CSS. Focused interview preparation with visualizers and drills. A resume builder to show it all off. One place, zero setup.

Start practising Mock interview Build resume
  • 12tools
  • 3tracks
  • 5resume templates
  • 100%offline & private
1

Practice

Write code, run it, get instant feedback.

Start here

JS Lab

JavaScript & React coding questions with an in-browser runner, console and automatic test checks.

Open JS Lab

React Lab

Build components with hooks and watch renders, effects and timers as they happen.

Open React Lab

CSS Lab

HTML & CSS challenges with a live preview and automatic checking of your solution.

Open CSS Lab
2

Interview Prep

Understand the fundamentals interviewers actually ask about.

Algorithms

Step through sorting and searching algorithms and compare how they behave side by side.

Open Algorithms

JS Concepts

Guided lessons on closures, the event loop, prototypes, async and more, with runnable examples.

Open JS Concepts

React Concepts

Rendering, state snapshots, effects, refs, memo and hooks — with live sandboxed examples and predict-the-output quizzes.

Open React Concepts

SQL & Regex

Query an in-browser SQLite database and learn regular expressions with a live tester and guided challenges.

Open SQL & Regex

Big-O

See how complexity classes grow and keep the cheat sheets for common data structures handy.

Open Big-O
3

Tools

Rehearse, tinker, revise — and get hired.

Mock Interview

Timed interview sessions with a mixed question set, scoring and a history of your attempts.

Start interview

Editor

A scratch editor for JavaScript and React experiments with a live preview and console.

Open Editor

Flashcards

Flashcards and quick quizzes to lock in the concepts you've just learned.

Open Flashcards New

Resume Builder

Turn a simple form into a polished resume — fresher and experienced modes, five templates, PDF export.

Build resume

Practised enough? Put it on paper.

The Resume Builder turns a guided form into a recruiter-ready resume. Pick a template, tune the accent, and download a clean A4 PDF — no account, no watermark.

  • Fresher and experienced layouts with tailored section order
  • Live strength meter with tips on quantifying impact
  • Autosaves locally; export and import as JSON
Open Resume Builder
Classic Modern Sidebar Minimal Compact