OpenAI: GPT-5 Chat

openai/gpt-5-chat

Chat

GPT-5 Chat is designed for advanced, natural, multimodal, and context-aware conversations for enterprise applications.

vision

MODALITIES

→

INPUT PRICE

$1.25per 1M

OUTPUT PRICE

$10per 1M

CONTEXT

128K

RELEASED

Aug 8, 2025

Provider				Cache	Uptime	Chat
FastAPI	—	$1.25	$10	Cache read$0.125

Capabilities

Input modalities

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Output modalities

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Features

max_tokensresponse_formatseedstructured_outputs

Get your API key

Create an API key from the Keys page, then set it as an environment variable:

export ONLIST_API_KEY=sk-...

Make your first request

Endpoints

POSThttps://onlist.io/v1/chat/completions

OpenAI Chat Completions format

Request Headers

Authorization:Bearer $ONLIST_API_KEY

Content-Type:application/json

Model:openai/gpt-5-chat

POSThttps://onlist.io/v1/responses

OpenAI Responses format

Request Headers

Authorization:Bearer $ONLIST_API_KEY

Content-Type:application/json

Model:openai/gpt-5-chat

POSThttps://onlist.io/v1/messages

Anthropic Messages format

Request Headers

Authorization:Bearer $ONLIST_API_KEY

Content-Type:application/json

Model:openai/gpt-5-chat

Code samples

curl https://onlist.io/v1/chat/completions \
  -H "Authorization: Bearer $ONLIST_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
       "model": "openai/gpt-5-chat",
       "messages": [
         {
           "role": "user",
           "content": "Explain quantum entanglement in one paragraph."
         }
       ]
     }'

Replace $ONLIST_API_KEY with the API key from your Keys page.

Authentication

All requests must include an Authorization: Bearer <TOKEN> header. Generate keys from the Keys page; keys can be scoped to specific models, groups, IP ranges, and rate limits.

Enable streaming

Add "stream": true to receive partial responses as server-sent events in real time.

Streaming example

curl https://onlist.io/v1/chat/completions \
  -H "Authorization: Bearer $ONLIST_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
       "model": "openai/gpt-5-chat",
       "messages": [
         {
           "role": "user",
           "content": "Write a haiku about recursion."
         }
       ],
       "stream": true
     }'

Supported parameters

Name	Type	Description
`max_tokens`	integer	Maximum number of tokens to generate in the completion.
`response_format`	object	Specifies the output format. Use {"type": "json_object"} for JSON mode.
`seed`	integer	If specified, the system will attempt deterministic sampling for reproducible results.
`structured_outputs`

These are the request parameters this model accepts. Parameter semantics follow the OpenAI Chat Completions specification.