missing_api_key

Status: 401 · Code: missing_api_key

Your request reached the send0 API without an Authorization header.

Common causes

You forgot to set the header
A proxy or gateway stripped the header before it reached us
A typo in the header name (Authorisation, lowercase authorization is fine, anything else is not)

Add the header to every request:

Authorization: Bearer sk_live_xxxxxxxxxxxxxxxx

If you're using the SDK, pass the key to the constructor instead:

const client = new Send0('sk_live_xxxxxxxxxxxxxxxx')

Get a key at app.send0.dev/api-keys. Use sk_test_... in development — it never delivers real mail.