API reference

A REST API over HTTPS with predictable resources and JSON responses. Every operation a key can call has a page here, generated from the OpenAPI document the API itself publishes.

Conventions

Resource URLs are stable. Writes take JSON, and updates are POST requests to the object's URL. Amounts are integers in the smallest currency unit, and timestamps are Unix seconds in UTC.

curl https://api.billkit.eu/v1/subscriptions/sub_Pv9Kc3nX8mQ2rTyLbd \
  -H "Authorization: Bearer $BILLKIT_API_KEY"

Pagination

List endpoints are cursor-based. Pass limit and page with starting_after, which takes the last id you saw. Responses carry has_more; never infer the end of a list from a short page. limit defaults to 10 and is capped at 100. Paging is forward-only, so to go back, keep the cursors you have already used.

Versioning

There is one version of the API, v1, and it is the path prefix on every request. Requests carry no version header and accounts are not pinned to a dated version. Instead, v1 only changes in additive ways, under a compatibility contract that lists what can change without notice, what cannot, and what your integration has to tolerate. Anything else goes through the deprecation policy, and the API changelog records every notable change.

The version on this site, v1.1.0, is the version of the OpenAPI document behind these pages. It versions the document, not your account, and there is nothing to send it in.

Resources

91 operations, every one of them reachable with an API key. Each has its own page, generated from the OpenAPI document and its required scope. To filter the whole surface in one view, use the explorer.