GPT-5.5 and GPT-5.5 Pro Are Now Available in Puter.js

Puter.js now supports GPT-5.5 and GPT-5.5 Pro, OpenAI's newest frontier models for complex professional work and expert-level reasoning. Add them to your application for free without needing an OpenAI developer account or API key.

What is GPT-5.5?

GPT-5.5 is OpenAI's latest frontier model, released on April 24, 2026. It's the first fully retrained base model in the GPT-5 family, designed to plan, use tools, and carry multi-step tasks to completion autonomously. Key highlights include:

• 1.05M token context window — the first OpenAI API model to ship with a 1M+ context window
• 128K output tokens — generate long, detailed responses, code, and reports in a single call
• State-of-the-art agentic coding — 82.7% on Terminal-Bench 2.0 and 88.7% on SWE-Bench
• Top knowledge work scores — 84.9% on GDPval across 44 occupations
• Computer use — 78.7% on OSWorld-Verified for autonomous desktop operation
• 60% fewer hallucinations compared to GPT-5.4
• Full Responses API tool suite — web search, computer use, MCP, hosted shell, and tool search

It outperforms Claude Opus 4.7 and Gemini 3.1 Pro on most agentic and math benchmarks, defaults to medium reasoning effort, and supports the full range from none through xhigh.

What is GPT-5.5 Pro?

GPT-5.5 Pro is a higher-compute version of GPT-5.5 that uses more reasoning time to produce smarter, more precise responses on the hardest problems. It scores:

• 39.6% on FrontierMath Tier 4 — expert-level mathematics, nearly double Claude Opus 4.7's 22.9%
• 43.1% on Humanity's Last Exam — multidisciplinary zero-shot reasoning

GPT-5.5 Pro shares the same 1.05M token context window and 128K output limit as GPT-5.5. It's best suited for legal review, financial modeling, scientific research, and scenarios where first-pass accuracy outweighs cost and latency.

Examples

Basic Chat

puter.ai.chat("Draft a product launch plan for an AI-powered analytics tool", {
    model: "gpt-5.5"
})

Agentic Coding

puter.ai.chat(
    "Refactor this Express app into a modular structure with proper error handling, " +
    "request validation, and integration tests for each route.\n\n" + sourceCode,
    { model: "gpt-5.5" }
)

Expert Reasoning with Pro

puter.ai.chat(
    "Derive a closed-form solution for this stochastic differential equation " +
    "and verify the result with a Monte Carlo simulation outline.",
    { model: "gpt-5.5-pro" }
)

Streaming Responses

const response = await puter.ai.chat(
    "Explain how transformer architectures handle long-context inputs",
    { model: "gpt-5.5", stream: true }
);

for await (const part of response) {
    if (part?.reasoning) puter.print(part?.reasoning);
    else puter.print(part?.text);
}

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-5.5 immediately.

Learn more:

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