Customers API

What this does

The Customers API lets you manage your customer records programmatically. You can create new customers, retrieve the full list, update details, and delete customers you no longer need.

When to use it

Use this endpoint to sync customer data from your CRM, e-commerce platform, or any external system into Relentify.

Endpoints

List customers

GET /api/v1/customers

Returns a paginated list of customers. Supports ?page=1&limit=50 and ?search=name query parameters.

Create a customer

POST /api/v1/customers

{
  "name": "Acme Ltd",
  "email": "[email protected]",
  "phone": "020 7946 0958",
  "address": {
    "line1": "10 Downing Street",
    "city": "London",
    "postcode": "SW1A 2AA",
    "country": "GB"
  },
  "vatNumber": "GB123456789"
}

Response (201 Created):

{
  "id": "cust_abc123",
  "name": "Acme Ltd",
  "email": "[email protected]",
  "createdAt": "2026-03-31T10:00:00Z"
}

Get a single customer

GET /api/v1/customers/:id

Update a customer

PUT /api/v1/customers/:id

Pass the full customer object with updated fields.

Delete a customer

DELETE /api/v1/customers/:id

Deletes the customer record. This will fail if the customer has any associated invoices or credit notes. Void or delete those first.