LongCat API Quick Start: OpenAI-Compatible Setup

This independent guide summarizes the documented setup flow for sending a basic request to the LongCat API through its OpenAI-compatible interface. Always review the cited primary documentation before using an API in production.

Before you begin

You need a LongCat API Platform account and an API key created from the platform.

API keys are sensitive credentials. Store them securely and do not place them in browser-side code or public repositories.

• Create an API key in the platform after registering and signing in.
• Copy the key when it is created and store it securely.
• Use environment variables or a secure secret manager in production.

This site does not issue, manage, or bill for LongCat API keys.

Choose the OpenAI-compatible endpoint

The LongCat API documentation lists an OpenAI-compatible base URL for chat completion requests.

The documented OpenAI-compatible base URL is shown below.

https://api.longcat.chat/openai

Send a basic chat completion request

The documented chat completion endpoint uses the OpenAI-compatible path `/v1/chat/completions`.

Replace `YOUR_API_KEY` with your own secret value. Do not expose it in client-side code.

curl https://api.longcat.chat/openai/v1/chat/completions \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "LongCat-2.0",
    "messages": [
      {
        "role": "user",
        "content": "Hello"
      }
    ]
  }'

Understand compatibility

LongCat documentation describes support for OpenAI-compatible and Anthropic-compatible API formats.

This guide uses the OpenAI-compatible format because it is widely supported by common SDKs and HTTP clients.

• OpenAI-compatible chat completions use `/openai/v1/chat/completions`.
• Anthropic-compatible messages use `/anthropic/v1/messages`.
• Review the current API documentation before selecting a model or deploying an integration.

Next steps

After a basic request works, review the API documentation for available models, request options, usage, and error handling.

For a source-based model overview, see the LongCat-2.0 page on this site.

API availability, models, limits, pricing, and terms can change. Confirm current details in the cited primary documentation.

Related model

Sources

• LongCat API Quick Startofficial
  • Accessed: 2026-07-16
  • Documentation for account setup, API key creation, and API compatibility.
• LongCat API Overviewofficial
  • Accessed: 2026-07-16
  • Documentation for base URL, Bearer authentication, and API endpoints.

Review primary documentation before making production, commercial, or legal decisions.