GPT-5.3-Codex Is Now Available in Puter.js

Puter.js now supports GPT-5.3-Codex, OpenAI's most capable agentic coding model to date. Add it to your application for free without needing an OpenAI developer account or API key.

What is GPT-5.3-Codex?

GPT-5.3-Codex is OpenAI's flagship agentic coding model that combines frontier coding performance with strong general reasoning and professional knowledge capabilities. It advances both the coding performance of GPT-5.2-Codex and the reasoning capabilities of GPT-5.2. Key highlights include:

• 25% faster inference compared to GPT-5.2-Codex
• State-of-the-art on SWE-Bench Pro and Terminal-Bench
• Interactive agentic coding with real-time steering during multi-file tasks
• Stronger reasoning for research, tool use, and complex execution

GPT-5.3-Codex was notably the first model instrumental in creating itself, having been used to debug its own training and manage its own deployment.

Examples

Code Generation

puter.ai.chat(
    "Write a Python function that implements a thread-safe singleton pattern with lazy initialization",
    { model: "openai/gpt-5.3-codex" }
)

Code Refactoring

puter.ai.chat(
    "Refactor this class to use the repository pattern:\n\nclass UserService {\n  getUser(id) { return db.query('SELECT * FROM users WHERE id = ?', [id]); }\n  saveUser(user) { return db.query('INSERT INTO users VALUES (?)', [user]); }\n}",
    { model: "openai/gpt-5.3-codex" }
)

Security Analysis

puter.ai.chat(
    "Analyze this code for security vulnerabilities and suggest fixes:\n\napp.get('/user', (req, res) => {\n  const query = `SELECT * FROM users WHERE id = ${req.query.id}`;\n  db.query(query, (err, result) => res.json(result));\n});",
    { model: "openai/gpt-5.3-codex" }
)

Get Started Now

Just add one library to your project:

// npm install @heyputer/puter.js
import { puter } from '@heyputer/puter.js';

Or add one script tag to your HTML:

<script src="https://js.puter.com/v2/"></script>

No API keys or OpenAI developer account needed. Start building with GPT-5.3-Codex immediately.

Learn more:

• Free, Unlimited Codex API
• Free, Unlimited OpenAI API
• Puter.js AI Documentation