Quickstart

This guide takes you from nothing to your first answer from the Essentio Public API: create an API key, then list your Business’s Clients with it.

Create an API key

1. Sign in to Essentio and open Settings for the Business your software will work with.
2. Open the API Keys tab and create a key. Name it after the software that will use it, and choose its Role — Admin, Member or Viewer. A request with the key may do what that Role may do in Essentio.
3. Copy the key. It starts with ess_ and is shown once: Essentio keeps only a fingerprint of it, so a lost key cannot be shown again — revoke it and create another.

Keep the key on your server, never in a browser or a mobile app: anyone holding it acts for the Business.

Make your first request

Send the key as a bearer token. Listing Clients is open to every Role, so it works with any key:

curl https://api.essentio.pro/v1/clients \
  -H "Authorization: Bearer ess_your_api_key"

The answer is the first page of the Business’s Clients, oldest first:

{
  "data": [
    {
      "id": 42,
      "name": "Northwind Studio",
      "legal_name": "Northwind Studio Ltd",
      "contact_person": null,
      "email": "accounts@northwind.example",
      "phone": null,
      "address": "12 Harbour Street",
      "city": "Limassol",
      "postal_code": "3036",
      "country": "CY",
      "vat_number": "CY10000000X",
      "vat_verified": true,
      "account_code": "C0042",
      "currency": "EUR",
      "payment_terms": 30,
      "is_active": true,
      "created_at": "2026-09-01T09:30:00+00:00",
      "updated_at": "2026-09-01T09:30:00+00:00",
      "credit_limit": null,
      "notes": null,
      "preferred_bank_account_ids": []
    }
  ],
  "next_cursor": null
}

What's next?

• Authentication: what a key can do, and the answer to a request without one.
• Clients: every field of a Client, paging through them, and creating and updating one.
• Reports: Income, Reported VAT, Overdue and a Client’s Statement.
• The OpenAPI file: the whole contract, to generate a client from.