Getting started

Find your starting point.

A quick guide to choosing a question, using the workspace, and keeping your work. Practice what you need, at your own pace.

Begin with a challenge

Start small. Build something real.

Pick an easy question in a technology you know. Open the workspace, make your first edit, and check what happens. You can start coding without an account.

Find an easy challenge Browse all challenges

Use a desktop or laptop for coding. You can browse questions and study on mobile.

What would you like to build?

Choose a question that feels within reach.

A user interfacePractice components, state, and interactions.A JavaScript functionPractice language fundamentals and logic.

Get comfortable in the workspace

The question, your code, and the output stay together so you can focus on the next edit.

Problem

Understand the question

Read the problem and requirements first. Start with one behavior you can implement, then work through the rest.

Coding workspace

Make room to focus

Desktop challenges open in a full-viewport coding layout. Resize the editor and output panes, or use the fullscreen control for more room.

Editor & output

Build and check

Use Run to inspect your result. UI questions have a preview; JavaScript and TypeScript questions have console output. Where tests are configured, Run tests checks your current code.

Hints & solution

Get a little help

Open a hint when you need a nudge. Compare with the solution when you’re ready to review your approach, then try it again yourself.

See what the test cases check

Tests help you check behavior while you build. JavaScript and TypeScript questions can check function results and edge cases; configured UI checks render your component and interact with its controls.

Read the question’s test expectations. Input and expected output are visible when supplied.
Run tests to see which configured cases pass and which need another look.
Rerun after an edit: results belong to the version of your code that was tested.

Test coverage varies by question. Automated tests are available where a suite has been configured.

Examples from existing challenges

Flatten Array · JavaScript / TypeScript

Nested arrays flatten from left to right.

Input: [1, [2, [3]], 4]

Expected: [1, 2, 3, 4]

Counter · React / Vue / Angular

Browser checks click the button and inspect its label.

Starts with Clicks: 0
One click increments by one
Two clicks accumulate

Find a question that fits

Narrow down the question bank using the category tabs, filters, and search. You can also filter by topic or sort by creation date, difficulty, or estimated time in either direction.

Category: Switch between All Questions, UI Coding, and JavaScript.
Technology: Filter for the language or framework you want to practice.
Difficulty: Choose Easy, Medium, or Hard. Easy is a useful place to begin.
Search: Find a term in question titles and descriptions.

Start with a familiar technology. Each question lists its supported environments; when more than one is available, switch in the workspace selector. Each technology keeps its own draft.

JavaScript TypeScript React Vue Angular

Explore curated lists

Find these lists under Question bank → Curated lists. Choose a focus and practice at your own pace.

FineFrontend 75

Build frontend fundamentals with a focused selection of UI and JavaScript coding challenges.

Explore FineFrontend 75

Top Interview 100

Practice frontend interview problems covering component behavior, state, and JavaScript utilities.

Explore Top Interview 100

Top DSA 50

Strengthen problem-solving skills with data structures and algorithms, from arrays and strings to searching and traversal.

Explore Top DSA 50

Keep your work ready for next time

Start as a guest, then sign in when you want to save your practice to your account.

Try a question as a guest

Read the problem, edit the code, and run it without signing in. You can run any configured tests too. Your draft is kept in this browser tab; bookmarks, saved submissions, and account progress need a sign-in.

Start practicing

Save progress with your account

Keep drafts and bookmark questions. Submit a solution after its tests pass, then mark the challenge as Done. Use Your library to return to your work.

Build understanding beyond coding

Review interview questions, check your knowledge with MCQs, explore system design, or experiment in the playground.

Interview questions

Choose a technology and level. Try explaining a concept, then open the short answer and detailed explanation to compare.

Explore interview questions

MCQs

Choose an answer and check it. Read the explanation to strengthen your understanding or work out what you missed.

Try a knowledge check

System design

Explore questions such as news feeds and autocomplete, with visual explanations and detailed answers. Learn to discuss requirements, architecture, APIs, performance, and accessibility using the RADIO framework.

Explore system design

Playground

Switch between JavaScript and TypeScript, run your code, and inspect the console output. Experiment with an idea without a challenge brief.

Open the playground

Need a hand getting started?

Have a question, found an issue, or want to suggest a challenge? Tell us what would help.