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.

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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

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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

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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.

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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

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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!"}]
  }'

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GPT-5.5 Pro vs GPT-5.5 Standard