Which Programming Languages Can You Run in OnlineInterview.io's Code Editor?

Updated

OnlineInterview.io supports 12 languages in its browser-based code editor: C, C++, Go, Java, JavaScript, Julia, Kotlin, Lua, Python, Ruby, Rust, and TypeScript. You can select a language, provide program input, run the code, and check the output directly in the browser—no local setup or separate compiler needed. This applies to anyone using the platform's shared interview rooms for live coding sessions.

How the code editor works

The editor is a REPL-style environment with syntax highlighting. The workflow is:

  1. Select a language from the supported list.
  2. Write or paste code into the editor.
  3. Provide program input if your code reads from standard input.
  4. Run the code in the browser.
  5. Check the output in the results area.

Because execution happens in the browser, neither the interviewer nor the candidate needs to install a toolchain or configure a local environment before the session.

Supported languages at a glance

Language Typical interview use
C Systems fundamentals, memory concepts
C++ Algorithms, data structures, competitive-style problems
Go Backend and concurrency discussions
Java Enterprise and object-oriented design questions
JavaScript Frontend, full-stack, and general scripting
TypeScript Typed frontend and Node.js roles
Python Algorithms, scripting, data-oriented questions
Ruby Web development and scripting roles
Rust Systems programming and performance-focused roles
Kotlin Android and JVM-based roles
Lua Scripting and embedded use cases
Julia Numerical and scientific computing

What to check before your session

  • Input handling: If the problem requires reading from standard input, confirm the input format works as expected by running a small test before the interview starts.
  • Language version: The platform lists language names but does not publish version numbers, so avoid relying on version-specific syntax or libraries. If a question depends on a recent language feature, verify it in the editor beforehand.
  • Room capacity: Shared rooms allow up to three users at once—for example, one candidate and two interviewers—so plan your session around that limit.
  • Session saving: You can download the code and the drawing canvas image at the end, which is useful for keeping a record of what was written.

Practical example

Suppose you're interviewing for a Python role and want the candidate to solve a problem that reads a list of integers from standard input. You would select Python, paste the problem's starter code, and confirm that a sample input produces the expected output before sharing the room link. If the candidate prefers JavaScript, you can switch the language in the same session and re-run the same logic.

Bottom line

If your interview relies on any of the 12 listed languages, OnlineInterview.io's editor can run it in the browser with input and output support. If you need a language outside that list, or depend on a specific compiler version, test it in the editor first—the platform's published feature list does not go beyond the language names above.