The Connection API follows the BCF-API standard by buildingSMART. In a few places, BIMcollab adds requirements or works slightly differently. This article lists these differences so your application works correctly with BIMcollab.
💡 Tip: New to the Connection API? Read Getting started with the Connection API first.
Overview
Topic | What is different in BIMcollab |
Authorization request | The |
Updating issues | Always send the complete issue. |
Document and event services | Not supported. |
Modification dates | A comment change doesn't change the modification date of the issue. |
Viewpoints | Only the first viewpoint and viewpoints linked to a comment are visible. |
Authorization request
The BCF-API documentation shows an example authorization request without some parameters. BIMcollab requires two parameters in every authorization request:
scope: the permissions your application asks for. Example:openid offline_access bcf.redirect_uri: your callback URL.
Example:
https://playground.bimcollab.com/identity/connect/authorize?response_type=code&client_id=<client-id>&state=<state>&redirect_uri=<callback-url>&scope=openid%20offline_access%20bcf
For all steps, see How to authenticate with the BIMcollab API.
Updating issues: always send the complete issue
When you update an issue with PUT, the issue in BIMcollab is replaced by the data you send. Always send the complete issue, with all fields, and not only the fields you want to change.
If you only send the changed fields, other fields can lose their value.
The safest way to update an issue:
Get the issue with
GET /bc_2.1/projects/{project_id}/topics/{topic_guid}.Change the fields you want to update in the response.
Send the complete issue back with
PUT /bc_2.1/projects/{project_id}/topics/{topic_guid}.
📝 Note: This follows the HTTP standard. PUT replaces a resource. It doesn't update one part of it.
Document and event services
The BCF-API standard includes two services that the Connection API doesn't support:
Document services: documents linked to a project or issue.
Event services: the history of changes to issues and comments.
Requests to these services return empty data.
Alternatives:
To manage files in a BIMcollab space, use the Documents API. See Getting started with the Documents API.
To see what happened in a project, use the activity logs. See Retrieving activity logs and user access logs.
Modification dates
Issues and comments each have a modification date. This is important when your application synchronizes data: it checks the modification dates to find out what changed since the last sync.
The two versions handle comment changes differently:
Version | When a comment changes… |
| The issue's |
| The issue's |
In the Connection API, modified_date only shows when the issue data itself changed.
To find all changes in the Connection API, check both dates:
modified_date: the issue data changed, for example, the title or status.comments_modified_date: a comment on the issue was added or changed.
Example:
{
"globalId": "c0542e35-537d-441c-88bd-af0ad1407666",
"title": "Beam inside wall",
"modified_date": "2026-09-14T10:12:00+00:00",
"comments_modified_date": "2026-10-02T08:45:00+00:00"
}
In this example, the issue data last changed on September 14, but someone added or changed a comment on October 2.
Viewpoints
The BCF-API allows several viewpoints per issue. In BIMcollab, only the first viewpoint and viewpoints that are linked to a comment are visible to users.
For details and the recommended approach, see Working with viewpoints and comments in the Connection API.