Redmine

The current API does not provide all the required information for custom fields definitions.

There is a custom fields API (https://www.redmine.org/projects/redmine/wiki/Rest_CustomFields), but it requires administrator privileges and cannot be used by other users (see #18875 and #41318). I understand that this API is intended for admins only, but some data could be exposed to other users.

Since version 4.2.0 (#33301), the param /projects.json?include=issue_custom_fields has been introduced to provide project-related custom fields. However, only the ID and name are provided here. As requested in other feature requests (#18875 and #42581), it would be nice to receive more data about the definition of custom fields. In my opinion, at least the following fields should be exposed: field_format, multiple, is_required, default_value, and possible_values.

This would work for issues, but not for other resources such as time entry. I'm not sure where this information should best be provided, as something like include=time_entry_custom_fields would not be entirely correct for the projects api, since custom fields for time entries (TimeEntryCustomField) are not project-specific like IssueCustomField.

I maintain a Chrome extension for timer based time tracking and would like to add support for custom fields, but this is impossible without additional metadata.
It would be great if you could take a look at this and add more data. Thank you very much.