OpenAI GPT-5.5

GPT-5.5 is OpenAI's frontier model released on April 23, 2026, designed for complex professional workloads including agentic coding, computer use, and deep research. Building on GPT-5.4, it delivers stronger reasoning, higher reliability with 60% fewer hallucinations, and improved token efficiency — matching GPT-5.4 per-token latency while performing at a significantly higher level of intelligence. It features a 1M+ token context window (922K input, 128K output) with support for text and image inputs.

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Why It Looks Great

• Frontier-class reasoning with 88.7% SWE-bench Verified and 92.4% MMLU scores
• 1M token context window for large-scale reasoning, coding, and multimodal workflows
• 60% fewer hallucinations compared to GPT-5.4 with improved token efficiency
• Three variants: standard, Thinking (extended reasoning), and Pro (highest accuracy)
• Same per-token latency as GPT-5.4 despite the intelligence leap

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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 (low / medium / high / xhigh effort levels)
• Variants: GPT-5.5, GPT-5.5 Thinking, GPT-5.5 Pro

Benchmarks

Specifications

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Note: GPT-5.5 is 2× GPT-5.4 at the token level, but uses significantly fewer tokens to complete the same tasks. Independent testing puts the net cost increase at roughly 20% once token efficiency is factored in.

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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 processes your request and returns the response.

API Integration

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

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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",
    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",
    "messages": [{"role": "user", "content": "Hello!"}]
  }'

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What's New vs GPT-5.4