Chat with Claude, free in your browser
Anthropic's Claude. Popular with developers for code and clear, careful answers.
Updated June 2026
Choose a model
Claude is Anthropic's model family. A lot of developers reach for it when they're writing or reviewing code, or when they want an answer that's organized and easy to follow. You can chat with Claude on OneCompiler from the browser, with streaming replies and copyable code.
Claude tends to do well on programming, refactoring, and working through long inputs without losing the thread. The answers are usually thorough without a lot of filler.
Claude Haiku is the fast one, which makes it a good everyday pick. Opus and Sonnet are stronger on hard reasoning and the trickier coding tasks. You can switch between them from the picker whenever you want.
Learn more about Claude on the official site
Best for
- Writing and reviewing code
- Long files and documents
- Clear, structured explanations
- Following instructions closely
Claude models on OneCompiler
| Model | Good for | Plan |
|---|---|---|
| Claude Haiku 5.5 | Fast and light. A good everyday default. | Plus and above |
| Claude Sonnet 5.5 | A balance of speed and strength for harder tasks. | Pro and above |
| Claude Opus 5.5 | The most capable, for the toughest coding and reasoning. | Pro and above |
| Claude Fable 5.1 | Anthropic's most capable model, for the hardest problems. Max plan. | Max and above |
What you can do with Claude
- Review a function or a pull request for bugs
- Refactor messy code without changing what it does
- Read a long file and explain what it does
- Turn a spec into working code
- Write clear documentation and comments
- Talk through a tricky design decision
How it works
- 1. Pick a Claude model above and choose Start chatting.
- 2. Ask your question — answers stream in with syntax-highlighted code.
- 3. Copy any code block, or paste it into the OneCompiler editor to run it in the browser.
How Claude compares
Claude is a common first choice for programming and for prompts with a lot of context. Compared with GPT, people often find its code and explanations cleaner; compared with the lighter models, it trades a little speed for more careful answers. If your work is mostly code review, refactoring, or long files, Claude is worth trying before the others.
Frequently asked questions
Is Claude free here?
The Claude models are premium here and need a paid plan. Haiku is the quick one for everyday questions.
Which Claude is best for coding?
Opus is the strongest for hard coding and reasoning. Haiku is a fast default for everyday use.
Can Claude handle long inputs?
Yes. It's good at keeping track of a lot of context, so it works well with long files and documents.
Can Claude write and run code?
Code is one of Claude's strengths. It returns copyable blocks; to run them, paste into the OneCompiler editor, which supports 110+ languages.
Do I need an Anthropic account or API key?
No Anthropic account and no API key. You sign in to OneCompiler to start chatting and to keep your history.
Is my conversation private?
Yes. Your chats are private by default and only become visible to others if you choose to share one.