Where's my API key and how do I send a signature via the API?

Your API key is generated in your account settings, Integrations / API section. With the key in hand, you call Certyneo's REST API to create an envelope: you provide the document, the signers and the fields, and the API returns the envelope ID plus the signing links.

You can track progress via webhooks that notify your app on every event (document signed, declined, etc.). Tip: start with a test key, and scope your calls to the right workspace (workspaceId) if you have more than one.