Versioning policy

One version

There is no version number in the API URL. The Out API has a single version that evolves in a backward-compatible way. Every change is published in the changelog.

Backward-compatible changes

The following changes do not break existing integrations; they may be made without prior notice and are recorded in the changelog:

• Adding a new endpoint.
• Adding new fields to responses.
• Adding new optional fields to requests.
• Adding an error code to an error that had none, or making error messages clearer.
• Bug and security fixes.

Breaking changes

Removing an endpoint or field, changing a field's meaning or format, and adding a required request field are breaking changes. For these:

1. The change is announced in the changelog at least 90 days before it takes effect.
2. The affected endpoint is marked To be removed in the docs; its page shows the date and the replacement.
3. On that date the removed endpoint starts returning HTTP 410.

Keep your integration resilient

• Ignore response fields you do not recognise; new fields may be added without notice.
• Expect fields with empty values to be left out of the response.
• Branch on Result and ErrorCode; the ErrorMessage text may change.
• Treat an unknown ErrorCode as a general error and log it.
• On 00001 or 00006, get a new ApiCode with DoLogin and retry the request once.
• Follow the changelog regularly.