KiosAPI Authentication — API Key and Header Formats

Pass your KiosAPI API key in the correct HTTP header for OpenAI-compatible, Claude native, and Gemini native endpoints — with curl examples.

Every request to KiosAPI requires an API key passed in the HTTP headers. The header format you use depends on which endpoint you’re calling — OpenAI-compatible endpoints, Claude native, and Gemini native each follow their own convention.

API Key

Your KiosAPI API key follows this format:

sk-kilo-xxxxxxxxxxxxxxxxxxxxxxxxxxxx

Treat your key as a secret. Never expose it in client-side code, commit it to version control, or write it to logs. Load it at runtime using environment variables or a secrets manager.

OpenAI Format (Bearer Header)

Use this header when calling the OpenAI-compatible endpoints (/v1/chat/completions or /v1/responses):

curl https://kiosapi.com/v1/chat/completions \
  -H "Authorization: Bearer sk-kilo-xxxxxxxxxxxx" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-4o",
    "messages": [
      {"role": "user", "content": "Hello!"}
    ]
  }'

Header	Value
Authorization	Bearer sk-kilo-xxxxxxxxxxxx
Content-Type	application/json

This is the most common format. OpenAI SDK libraries send this header automatically when you set api_key on the client — you don’t need to add it manually.

Claude Native Format (x-api-key + anthropic-version)

Use these headers when calling the Claude native endpoint (/v1/messages):

curl https://kiosapi.com/v1/messages \
  -H "x-api-key: sk-kilo-xxxxxxxxxxxx" \
  -H "anthropic-version: 2023-06-01" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-sonnet-4-20250514",
    "max_tokens": 1024,
    "messages": [
      {"role": "user", "content": "Hello!"}
    ]
  }'

Header	Value
x-api-key	sk-kilo-xxxxxxxxxxxx
anthropic-version	2023-06-01
Content-Type	application/json

The anthropic-version header is mandatory for the Claude native endpoint. Omitting it returns a 400 Bad Request error.

Gemini Native Format (x-goog-api-key)

Use this header when calling the Gemini native endpoint (/v1beta/models/{model}:generateContent):

curl "https://kiosapi.com/v1beta/models/gemini-2.5-flash:generateContent" \
  -H "x-goog-api-key: sk-kilo-xxxxxxxxxxxx" \
  -H "Content-Type: application/json" \
  -d '{
    "contents": [
      {"parts": [{"text": "Hello!"}]}
    ]
  }'

Header	Value
x-goog-api-key	sk-kilo-xxxxxxxxxxxx
Content-Type	application/json

Getting Your API Key

1. Log into kiosapi.com

   Go to kiosapi.com and sign in to your account.

2. Navigate to Dashboard > Token Management

   Open the Dashboard and select Token Management from the menu.

3. Create or copy your token

   Create a new token or copy an existing one to use in your requests.

Your API key carries full access to your KiosAPI account. Never share it publicly, commit it to version control, or embed it in client-side applications. Use environment variables or a secrets manager to load it at runtime.

KiosAPI keys are not interchangeable with keys from OpenAI, Anthropic, or Google. Always use a KiosAPI key (sk-kilo-...) with kiosapi.com, and never send it to api.openai.com, api.anthropic.com, or googleapis.com — it will be rejected. Likewise, third-party provider keys will not work with kiosapi.com. Mixing up base URLs and keys is the most common cause of 401 Unauthorized errors.