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GPT-5.3-Codex
openai/gpt-5.3-codexGPT-5.3-Codex is OpenAI’s most advanced agentic coding model, combining the frontier software engineering performance of GPT-5.2-Codex with the broader reasoning and professional knowledge capabilities of GPT-5.2. It achieves state-of-the-art results...
Context
400K tokens
Input, 1M tokens
$2.01
Output, 1M tokens
$16
Benchmark
—
Uptime and speed
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Pricing
Charged from your prepaid balance for the tokens actually used.
Input tokens$2.01 per 1M tokens
Output tokens$16 per 1M tokens
Cache read$0.2 per 1M tokens
Apps and activity
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Technical details
Model IDopenai/gpt-5.3-codex
Context window400K tokens
AcceptsText, Images, Files, pdf
ProducesText
TokenizerGPT
Max output tokens128,000
How to connect
The API is OpenAI-compatible: the official SDKs, LangChain and any client with a "base URL" field work.
import OpenAI from 'openai'
const client = new OpenAI({
baseURL: 'https://getmegabrain.com/api/gateway/v1',
apiKey: process.env.MEGABRAIN_API_KEY,
})
const response = await client.chat.completions.create({
model: 'openai/gpt-5.3-codex',
messages: [{ role: 'user', content: 'Hello!' }],
})Start using GPT-5.3-Codex
Create a free account, get a key in your dashboard and send your first request. Top up your balance when you need it.