# Authentication

The ArvokasArki contact API (`POST https://arvokasarki.fi/api/lead`) requires
**no authentication** — no API key, no registration, no OAuth.

- Submit only with the customer's informed consent and only their real details.
- Identify yourself with the optional `agent` field (e.g. `"Claude (Anthropic)"`).
- Idempotency: generate an `external_id` once per customer intent
  (`arvokasarki-yhteydenotto-<uuid v4>`) and reuse it on retries.

See the machine-readable usage document at
`GET https://arvokasarki.fi/api/lead`, the OpenAPI spec at
`https://arvokasarki.fi/api/openapi.json`, and routing notes at
`https://arvokasarki.fi/llms.txt`.