Authentication and URLs

Send API keys in request headers. Never place them in URLs, frontend JavaScript, public configuration, or ordinary application logs.

OpenAI compatible and Responses

Authorization: Bearer sk-your-key
Content-Type: application/json

Bearer must be followed by one space. Replace only sk-your-key. The base URL is:

https://sprelaytoken.com/v1

Claude Messages

x-api-key: sk-your-key
anthropic-version: 2023-06-01
content-type: application/json

x-api-key contains the key without a Bearer prefix. anthropic-version selects the protocol version. Claude SDKs use this root base URL and append /v1/messages:

https://sprelaytoken.com

Gemini Native

x-goog-api-key: sk-your-key
Content-Type: application/json

The model is part of the native request path:

https://sprelaytoken.com/v1beta/models/{model}:generateContent

Environment variables

macOS / Linux

# Replace only the placeholder; later commands read this variable.
export SPRELAY_API_KEY="sk-your-key"

Windows PowerShell

# This value is temporary and applies to the current PowerShell session.
$env:SPRELAY_API_KEY = "sk-your-key"

.env (do not commit)

# .env uses KEY=VALUE without export or spaces around the equals sign.
SPRELAY_API_KEY=sk-your-key

Add .env to .gitignore. Commit only an empty .env.example.

Common URL mistakes

Resulting URL	Cause
.../v1/v1/chat/completions	Both the client and configuration appended /v1
.../chat/completions/chat/completions	A complete endpoint was entered in a Base URL field
Claude path with OpenAI JSON	The endpoint and request body use different protocols
Gemini SDK with an unexpected Bearer header	The SDK expects its API-key option or x-goog-api-key