Requests and responses

Every endpoint speaks the same JSON. Learn it once here, and the reference only has to tell you what is different.

Base URL#

Send every request over HTTPS to the version you build against:

Base URL

https://api.welly.no/v1

Methods and paths#

Paths name things in the plural, in lower case: /v1/enrolments, /v1/enrolments/{enrolment}. The method says what happens:

Method	What it does
`GET`	Reads. It never changes anything.
`POST`	Creates something, or does an action such as `/cancel`.
`PATCH`	Changes some fields of something.
`DELETE`	Removes something.

A request body is JSON, sent with Content-Type: application/json. A field the endpoint does not know is refused with parameter_unknown, so a typo is never silently ignored.

Resources#

A resource is a JSON object. Its object field says what it is, and its id is a public id that never changes. Keys are in snake_case.

A resource (example)

{
  "object": "enrolment",
  "id": "pe8fdsi3tthy5hsaacus8cg5bfms",
  "program": "pmch6aid5frt4rye3ipupwxsn2ux",
  "status": "active",
  "starts_on": "2026-11-02",
  "created": "2026-10-12T09:41:07Z"
}

Examples, not endpoints. Objects such as enrolment show the conventions. They are not in the API yet; the reference lists what is.

Ids, times and money#

Ids are strings such as pe8fdsi3tthy5hsaacus8cg5bfms. Store them as they are; the first two letters say what kind of thing it is.
Times are RFC 3339 in UTC, ending in Z: 2026-10-12T09:41:07Z.
Dates without a time are YYYY-MM-DD and mean that day where the member lives: starts_on.
Money is an exact decimal string with its currency, never a floating-point number: {"amount": "24990.00", "currency": "NOK"}.
null means the field is not set.

Members are never named#

The API gives a member by their id. It never gives a member's name, e-mail address, phone number or date of birth, unless an endpoint exists for that purpose and your agreement covers it.

Lists#

An endpoint that returns many things returns a list, a page at a time. See Pagination.

Field	Type	Meaning
`object`	`"list"`	Always `list`.
`data`	array	The page of resources, at most `limit` of them.
`has_more`	boolean	Whether there is a next page.
`next_cursor`	string or null	Pass it as `starting_after` for the next page.

Errors#

A request that fails gets an HTTP status from 400 up and an error object. Act on type and code; the message is for people and may change. See Errors.

404 Not Found

{
  "error": {
    "type": "invalid_request_error",
    "code": "resource_missing",
    "message": "No such endpoint: GET /v1/pong",
    "param": null,
    "doc_url": "https://developer.welly.no/docs/errors#resource_missing",
    "request_id": "req_6b1d0c9e2f4a4d1c"
  }
}

Headers#

Every response is JSON, is never cached (Cache-Control: no-store), and has a Welly-Request-Id header.

Keep the request id. Log the Welly-Request-Id of every request. Send it to us when you ask about a request, and we can find it at once.