API Key and Base URL explained for OpenAI-compatible APIs

Before you read this guide

This guide explains the basic concepts of API keys, Base URLs, endpoints and OpenAI-compatible APIs. Read it before configuring Cursor, Claude Code, Codex CLI, Cline, Continue, Open WebUI or any other tool that asks for these fields.

No technical background is assumed beyond familiarity with copying text and running terminal commands.

How to start with RutaAPI

curl https://api.rutaapi.com/v1/models \
  -H "Authorization: Bearer YOUR_RUTAAPI_KEY"

curl https://api.rutaapi.com/v1/chat/completions \
  -H "Authorization: Bearer YOUR_RUTAAPI_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "MODEL_NAME",
    "messages": [
      {"role": "user", "content": "Hello from RutaAPI"}
    ]
  }'

Who this guide is for

This guide is for anyone who has been asked for an API key, Base URL or model name by an AI tool and did not know what to fill in.

If you already know what an API key and Base URL are, jump to the correct examples section.

Who should not use this guide alone

• Users who already have a working API key and Base URL — use the RutaAPI Docs directly.
• Users who only want pricing information — see Pricing instead.

Testing your key and Base URL

Before configuring any AI tool, test the API key and Base URL from the terminal first. This rules out configuration errors before you touch any tool settings.

If the terminal request succeeds, the tool configuration should work too. If it fails, fix the terminal request first — terminal errors are easier to diagnose than tool-specific error messages.

How to pick a model name

Model names are returned by the GET /v1/models endpoint. Copy one of the model id values from the response and use it wherever the tool asks for a model name.

Model availability is per-account. If a model name is not in your /v1/models response, it is not active in your account.

Common errors

401 Unauthorized

The API key is missing, incorrect, or sent to the wrong Base URL. Verify the key and Base URL both come from the same platform.

403 Forbidden

The key exists but lacks permission. Check credits and model access in your account.

404 Model not found

The model name is not in your account. Run GET /v1/models and copy a returned model id.

429 Too Many Requests

Rate or concurrency limit. Lower the number of concurrent requests and retry.

503 Service Unavailable

The provider route is temporarily unavailable. Try a short request or contact support if persistent.

Tools that ask for these fields

• Cursor and Cursor Composer
• Claude Code
• Codex CLI
• Cline
• Continue
• Open WebUI
• Any tool that supports custom OpenAI-compatible providers

When RutaAPI may help

• You need an OpenAI-compatible Base URL and API key in one place
• You want prepaid credits instead of a monthly contract
• You want to verify available models with /v1/models before configuring any tool
• You want setup docs for Cursor, Claude Code, Codex CLI and similar tools
• You want usage visibility — requests made, models used, credits remaining

When RutaAPI may not help

• You need a direct contract with a specific model provider
• You require guaranteed availability of one exact model with no routing
• You need an official provider-only enterprise contract

Related guides

• Unified Base URL for Claude Code, Codex CLI and Cursor
• Cursor custom API setup guide
• Codex CLI setup with RutaAPI
• Claude Code setup with RutaAPI
• Codex CLI invalid_api_key troubleshooting
• Claude Code timeout troubleshooting
• Available models
• Pricing and credit packs