OpenAI GPT-5.5 Pro

GPT-5.5 Pro is the highest-accuracy variant of OpenAI's GPT-5.5 frontier model, released April 23, 2026. It applies parallel test-time compute on top of the same GPT-5.5 base model to maximize correctness on hard tasks — targeting professional research, complex multi-step analysis, and production-grade agentic workflows where getting the answer right matters more than speed or cost. Available to Pro, Business, and Enterprise users in ChatGPT, and via the Responses API for developers.

Why It Looks Great

• Highest-accuracy mode in the GPT-5.5 family, built for correctness-critical workloads
• 1M token context window (922K input, 128K output) for large-scale document reasoning
• Parallel test-time compute delivers stronger results on hard coding, research, and analysis tasks
• Same 60% hallucination reduction and multimodal capabilities as GPT-5.5 standard
• Responses API support for structured agentic tool-use workflows

Key Features

• Context Window: 1050000 tokens
• Max Input: 922000 tokens
• Max Output: 128000 tokens
• Vision: Supported
• Function Calling: Supported
• Thinking Mode: Supported (extended parallel reasoning)
• API: Responses API only

Benchmarks

Note: OpenAI has not published separate benchmark numbers for GPT-5.5 Pro vs standard. The Pro variant uses additional compute at inference time to improve accuracy beyond the standard model's scores.

Specifications

Pricing

GPT-5.5 Pro is 6× the standard GPT-5.5 price. Use it for tasks where correctness justifies the cost — complex research synthesis, high-stakes code generation, and production decision support. For routine workloads, GPT-5.5 standard at $5/$30 is the better fit.

How to Use

1. Write your prompt — describe the task, provide context, and specify desired output format.
2. Submit — the model applies extended parallel reasoning and returns the response.

API Integration

Base URL: https://llm.wavespeed.ai/v1 API Endpoint: responses Model ID: openai/gpt-5.5-pro

API Usage

Python SDK

from openai import OpenAI

client = OpenAI(
    api_key="YOUR_API_KEY",
    base_url="https://llm.wavespeed.ai/v1"
)

response = client.chat.completions.create(
    model="openai/gpt-5.5-pro",
    messages=[{"role": "user", "content": "Hello!"}]
)

print(response.choices[0].message.content)

cURL

curl https://llm.wavespeed.ai/v1/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "model": "openai/gpt-5.5-pro",
    "messages": [{"role": "user", "content": "Hello!"}]
  }'

GPT-5.5 Pro vs GPT-5.5 Standard