This is 2026.9 documentation. Coverage here is incremental: a page exists only where 2026.9
differs or is newly documented. For any other topic, switch to Current in the version
selector.
Building directly on the open-source Viewer package? This is the case most likely to break
silently, and it’s easy to miss in the general migration comms because it isn’t “just” an SDK or
API consumer.If your application imports the Viewer package itself — extending render pipelines, forking
extensions, reading render views/batches, or otherwise reaching into its internals, rather than
only embedding the hosted web viewer or reading data through the GraphQL/REST API — you’re
exposed as soon as any data you load has been converted to the 2026.9 format. There’s no
updated Viewer package to move to yet (see the note below), so the only mitigation right now is
compatibility mode, which keeps your workspace’s data in the format the current Viewer
already understands.We know that leaves you planning against a moving target: compatibility mode is currently
scheduled to end on 1 November 2026, and there’s no committed date yet for a Viewer package that
reads the 2026.9 format. Those two things are linked — by 1 November, either an alpha of the new
Viewer package will be available for developers in this position, or that deadline moves for you.
We don’t yet know which, but we’re not going to leave Viewer-package developers with neither. This
page will be updated as soon as that’s decided.Compatibility mode isn’t self-serve. Ask us to turn it on for your workspace(s) before 1
November 2026 via speckle.community/help or your Customer
Success Advisor — the sooner the better, since it can take time to reach the right person. See
Who’s affected in the data model
migration guide for the full picture. Package-level Viewer documentation is planned for when compatibility mode turns off on 1
November 2026. For the web 3D viewer in the product UI, see 3D viewer in
2026.9. 
