Playgrounds
Run code while you prepare
Online editors for popular languages, frameworks and databases. Test an answer, check syntax or work through a code challenge in your browser, with nothing to install.
Languages
JavaScript
Runs on RunJS
TypeScript
Runs on TypeScript Playground
Python
Runs on Trinket
Java
Runs on Sololearn
C#
Runs on .NET Fiddle
C++
Runs on Sololearn
PHP
Runs on OnlinePHPWeb and frameworks
HTML
Runs on Sololearn
jQuery
Runs on Sololearn
React
Runs on CodePen
Angular
Runs on StackBlitz
Node.js
Runs on StackBlitzDatabases
MySQL
Runs on OneCompiler
SQL Server
Runs on OneCompiler
SQLite
Runs on OneCompiler
MongoDB
Runs on OneCompiler
Editors are provided by third-party services and open in a new window. Their own terms and privacy policies apply. Avoid entering personal or confidential information.
Using playgrounds
Practise coding questions the way interviews test them
- Read a question on the topic page, write your own solution in the editor, then compare it with the answer.
- Run edge cases such as empty input, large values and invalid data, as interviewers often ask about them.
- Time yourself. Most live coding rounds allow 20 to 45 minutes per problem.
- Explain your approach out loud as you type, which is what interviewers assess alongside the code itself.