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OpenKey

GPT-5.5 Pro

OpenAIReleased Apr 24, 2026

GPT-5.5 Pro is OpenAI’s high-capability model optimized for deep reasoning and accuracy on complex, high-stakes workloads. It features a 1M+ token context window (922K input, 128K output) with support for...

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Context window
1.1M tokens
Max output
128K tokens
Input
file, image, text
Output
text
Tokenizer
GPT
Knowledge cutoff
Dec 1, 2025
Released
Apr 24, 2026
Reasoning
always on

Pricing

Per 1M tokens. The provider price and our flat 3% fee are separate columns — what you pay is their sum.

Per 1M tokensProvider+ 3% feeYou pay
Input$30.00$0.900$30.90
Output$180.00$5.40$185.40

Supported parameters

  • include_reasoning
  • max_tokens
  • reasoning
  • response_format
  • seed
  • structured_outputs
  • tool_choice
  • tools

Call it

OpenAI-compatible: point your SDK at api.openkey.ai/v1 and use model openai/gpt-5.5-pro.

Code sample language
curl https://api.openkey.ai/v1/chat/completions \
  -H "Authorization: Bearer $OPENKEY_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-5.5-pro",
    "messages": [{"role": "user", "content": "Hello"}]
  }'
import os
from openai import OpenAI

client = OpenAI(
    base_url="https://api.openkey.ai/v1",
    api_key=os.environ["OPENKEY_API_KEY"],
)

completion = client.chat.completions.create(
    model="openai/gpt-5.5-pro",
    messages=[{"role": "user", "content": "Hello"}],
)
print(completion.choices[0].message.content)
import OpenAI from "openai";

const client = new OpenAI({
  baseURL: "https://api.openkey.ai/v1",
  apiKey: process.env.OPENKEY_API_KEY,
});

const completion = await client.chat.completions.create({
  model: "openai/gpt-5.5-pro",
  messages: [{ role: "user", content: "Hello" }],
});
console.log(completion.choices[0].message.content);

Questions

How much does GPT-5.5 Pro cost via API?
Through OpenKey, GPT-5.5 Pro costs $30.90 per 1M input tokens and $185.40 per 1M output tokens. That is the provider price ($30.00 / $180.00) plus a flat 3% fee — nothing else.
What is GPT-5.5 Pro's context window?
GPT-5.5 Pro accepts up to 1.1M tokens of context and returns up to 128K tokens per request.
Is GPT-5.5 Pro OpenAI-compatible?
Yes. Send requests to OpenKey's /v1/chat/completions endpoint with model "openai/gpt-5.5-pro" using any OpenAI SDK — only the base URL and API key change.
What inputs does GPT-5.5 Pro support?
GPT-5.5 Pro accepts file, image, text input and produces text output. Its knowledge cutoff is Dec 1, 2025.

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