OpenAIFastUltra

GPT-6 Astra

OpenAI's most capable model (GPT-6 generation, September 2026), built for the hardest end-to-end work: complex reasoning, coding, computer use, research and document creation. 1M token context window, 128K max output tokens, cached inputs at a 90% discount. Prompts above 272K input tokens are billed at 2x input / 1.5x output for the whole request.

18,580/92,900credits

input / output · per 1M tokens

Most capable OpenAI model (GPT-6 generation)

1M token context window

128K max output tokens

Knowledge cutoff: April 2026

Cached input pricing (90% discount)

Adjustable reasoning effort (low to max)

Function calling and native vision support

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Model Specifications

Context Window

tokens

Max Output

128K

tokens

Training Cutoff

2026-04

Compatible SDK

OpenAI

Capabilities

Vision

Function Calling

Streaming

JSON Mode

System Prompt

Token Pricing (per 1M tokens)

Token Type	Credits	USD Equivalent
Input Tokens	18,580	$12.39
Output Tokens	92,900	$61.93
Cached Tokens	1,858	$1.24

* 1,500 credits ≈ $1 (actual charges may vary based on usage)

Quick Start

curl -X POST "https://api.core.today/llm/openai/v1/chat/completions" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer cdt_your_api_key" \
  -d '{
  "model": "gpt-6-astra",
  "messages": [
    {
      "role": "system",
      "content": "You are a senior software engineer. Think step by step."
    },
    {
      "role": "user",
      "content": "Design a migration plan from a monolithic Express API to modular services, then generate the first service's code with tests."
    }
  ],
  "reasoning_effort": "high",
  "max_completion_tokens": 8000
}'

Parameters

Parameter	Type	Required	Default	Description
`messages`	array	Yes	-	Array of message objects with role and content
`model`	string	Yes	gpt-6-astra	Model identifier
`max_completion_tokens`	integer	No	4096	Maximum tokens in response (up to 128000). Note: use max_completion_tokens, not max_tokens
`reasoning_effort`	string	No	medium	Reasoning effort level: low, medium, high, xhigh, or max lowmediumhighxhighmax
`temperature`	float	No	1.0	Sampling temperature (0-2)
`stream`	boolean	No	false	Enable Server-Sent Events streaming

Examples

Frontier Agentic Coding

Multi-step code reasoning with GPT-6 Astra

curl -X POST "https://api.core.today/llm/openai/v1/chat/completions" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer cdt_your_api_key" \
  -d '{
  "model": "gpt-6-astra",
  "messages": [
    {
      "role": "system",
      "content": "You are a senior software engineer. Think step by step."
    },
    {
      "role": "user",
      "content": "Design a migration plan from a monolithic Express API to modular services, then generate the first service's code with tests."
    }
  ],
  "reasoning_effort": "high",
  "max_completion_tokens": 8000
}'

Cached Repeated Context

Reuse a large system prompt with 90% cached input discount

curl -X POST "https://api.core.today/llm/openai/v1/chat/completions" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer cdt_your_api_key" \
  -d '{
  "model": "gpt-6-astra",
  "messages": [
    {
      "role": "system",
      "content": "<large repeated system prompt or codebase context>"
    },
    {
      "role": "user",
      "content": "Summarize the open TODOs and rank them by risk."
    }
  ],
  "temperature": 0.3,
  "max_completion_tokens": 4000
}'