OpenAIFastUltra

GPT-5

OpenAI's latest flagship model. Delivers exceptional performance across reasoning, coding, and creative tasks with a massive 1M token context window and 32K output tokens. Supports vision, function calling, and JSON mode.

3 credits

per 1K tokens (avg)

1M token context window

32K max output tokens

Advanced reasoning capabilities

Native vision (text + image)

Function calling & JSON mode

Structured outputs

Streaming support

Use with AI Assistant

Copy usage instructions for Claude, ChatGPT, or other AI

llms.txt

Model Specifications

Context Window

1.0M

tokens

Max Output

33K

tokens

Training Cutoff

2025-03

Compatible SDK

OpenAI

Capabilities

Vision

Function Calling

Streaming

JSON Mode

System Prompt

Token Pricing (per 1M tokens)

Token Type	Credits	USD Equivalent
Input Tokens	2,500	$2.50
Output Tokens	20,000	$20.00
Cached Tokens	625	$0.63

* 1 credit ≈ $0.001 (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-5",
  "messages": [
    {
      "role": "system",
      "content": "You are an expert analyst. Provide thorough, well-structured analysis."
    },
    {
      "role": "user",
      "content": "Analyze the potential impacts of quantum computing on current encryption standards and suggest a migration roadmap for enterprise systems."
    }
  ],
  "max_completion_tokens": 4000
}'

Parameters

Parameter	Type	Required	Default	Description
`messages`	array	Yes	-	Array of message objects with role and content
`model`	string	Yes	gpt-5	Model identifier
`max_completion_tokens`	integer	No	4096	Maximum tokens in response (up to 32768). Note: use max_completion_tokens, not max_tokens
`stream`	boolean	No	false	Enable Server-Sent Events streaming
`response_format`	object	No	-	Format of response: { type: 'json_object' } for JSON mode
`tools`	array	No	-	List of tools (functions) the model can call
`reasoning_effort`	string	No	medium	Reasoning effort level: low, medium, or high

Examples

Complex Analysis

Multi-step reasoning and analysis with GPT-5

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-5",
  "messages": [
    {
      "role": "system",
      "content": "You are an expert analyst. Provide thorough, well-structured analysis."
    },
    {
      "role": "user",
      "content": "Analyze the potential impacts of quantum computing on current encryption standards and suggest a migration roadmap for enterprise systems."
    }
  ],
  "max_completion_tokens": 4000
}'

Code Generation

Generate production-quality code with GPT-5

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-5",
  "messages": [
    {
      "role": "system",
      "content": "You are an expert software engineer. Write clean, well-documented code."
    },
    {
      "role": "user",
      "content": "Create a TypeScript rate limiter middleware for Express.js that uses a sliding window algorithm with Redis for distributed rate limiting."
    }
  ],
  "max_completion_tokens": 4000
}'

JSON Data Extraction

Extract structured data from unstructured text

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-5",
  "messages": [
    {
      "role": "system",
      "content": "Extract structured data from the given text. Always respond with valid JSON."
    },
    {
      "role": "user",
      "content": "Parse this invoice: 'Invoice #2025-0842 from Acme Corp to Beta LLC, dated August 15 2025. Items: 10x Widget A at $25.00, 5x Widget B at $50.00. Tax: 10%. Shipping: $15.00'"
    }
  ],
  "response_format": {
    "type": "json_object"
  },
  "max_tokens": 1000
}'