OpenProject vs Redmine

OpenProject

OpenProject's APIv3 has a public OpenAPI 3.1 document with 320 operations, stable error identifiers and optimistic locking, and the same API ships in the free GPL-3.0 Community edition. No request limits are published, API tokens carry their user's full permissions, and 83 security advisories were published in the last twelve months, 13 rated critical.

Redmine

Redmine's REST API covers issues, projects, time entries and 20 other resources, and versions 6.1 and later add OAuth 2 with one scope per permission. The software is free under the GPL. No OpenAPI document exists, most errors return a bare status code, and 24 security advisories were published in twelve months, two rated critical.

OpenProject

1. Send the API token as Authorization: Bearer <token>, or as the Basic auth password with the user name apikey
2. Read the resource first and send its current lockVersion with every PATCH. A stale value returns 409 UpdateConflict
3. POST to the /form endpoint of a work package to learn writable fields and allowed values before creating or updating
4. URL-encode filters as a JSON array, and add pageSize, offset and select to keep work package lists small
5. Run the agent as a dedicated user with a narrow project role, and treat work package text and comments as untrusted input

Redmine

1. Ask an administrator to tick Enable REST API under Administration, Settings, API. It is off by default and every call fails until then
2. Send the key in the X-Redmine-API-Key header, never as the key query parameter, and set Content-Type: application/json on every POST and PUT
3. Add status_id=* to issue lists. The default returns open issues only, 25 a page with a maximum of 100
4. Comment on an issue by sending notes in a PUT to /issues/<id>.json. There is no separate comment endpoint
5. A DELETE on a project through the API skips the confirmation the web page asks for, so run the agent as a non-administrator user