Chat with GPT (OpenAI), free in your browser
OpenAI's GPT models. A solid all-rounder for writing, working through problems, and code.
Updated June 2026
Choose a model
GPT is OpenAI's model family, and it's the assistant most people have actually used. On OneCompiler you can chat with the latest GPT models right in the browser. No API key, nothing to install. Answers stream in as Markdown, with code blocks you can copy in one click.
GPT is a good default for almost anything: drafting text, summarizing, talking through an idea, or writing code in most languages. If you're not sure which model to pick, start here.
The smaller Mini and Nano models are quick and fine for everyday questions. Use GPT 5.5 when a problem needs more careful reasoning, or the Codex variant when you're mostly writing code. You can switch models any time from the picker, so it's easy to try a question on more than one.
Learn more about GPT (OpenAI) on the official site
Best for
- Everyday questions and writing
- Writing and explaining code
- Quick replies (Mini and Nano)
- Harder reasoning (GPT 5.5)
GPT (OpenAI) models on OneCompiler
| Model | Good for | Plan |
|---|---|---|
| GPT 5.4 Mini | Fast, capable default for everyday questions and code. | Free |
| GPT 5.4 Nano | The lightest and quickest, for short, simple replies. | Free |
| GPT 5.3 Codex | Tuned for code: generation, refactoring, and explanations. | Free |
| GPT 5.5 | The most capable, for hard reasoning and complex tasks. | Paid |
What you can do with GPT (OpenAI)
- Draft and edit emails, docs, and posts
- Generate code in Python, JavaScript, and 100+ other languages
- Explain an error message or a stack trace
- Turn rough notes into a clear summary
- Write unit tests for a function
- Brainstorm names, outlines, and approaches
How it works
- 1. Pick a GPT (OpenAI) 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 GPT (OpenAI) compares
GPT is the safe default when you don't have a strong preference. Claude tends to edge it out on careful coding and long inputs, and Gemini is often quicker for short lookups, but GPT covers the most ground across writing, reasoning, and code. Since switching models is one click, a good habit is to start with GPT and only reach for another when a task calls for it.
Frequently asked questions
Is it free?
Yes. Every GPT model here is free to use except the premium ones. Only premium models, like GPT 5.5, need a paid plan.
Which GPT model should I use?
Start with GPT 5.4 Mini. Use Nano if you want the fastest replies, the Codex variant for code-heavy work, and GPT 5.5 for the hardest problems.
Can GPT write and run code?
GPT writes code in most languages and returns it in copyable blocks. To run it, paste it into the OneCompiler editor, which executes 100+ languages in the browser.
Do I need an OpenAI account or API key?
No OpenAI account and no API key. You sign in to OneCompiler to start chatting and to keep your history.
Is my conversation private?
Yes. Chats are private to your account by default, and a chat is only visible to others if you choose to share it.
What languages does GPT understand?
GPT works across dozens of human languages and the major programming languages, so you can ask in your own language and get code in whichever one you need.