Massing's position is that your data should leave as easily as it arrived. IFC is the source of truth, and every derived artifact is regenerable.
A .mass file is one project: its model, all of its data, and its attachments, in a single file you
can copy, email, archive or commit to version control. It is a plain ZIP.
Format id massing.project, version 2, media type application/zip.
This is why samples ship as .mass rather than loose IFC: a sample opens as a project — geometry plus
every table — which is the whole difference between this and a viewer. Full specification in
mass-format.md.
There is also .mmproj via GET /projects/{id}/bundle and POST /projects/import-bundle for
project-bundle transfer.
| What | Notes |
|---|---|
| IFC (2x3, 4, 4.3) | The source of truth. Pre-converted to Fragments server-side. |
BCF (.bcfzip) |
Issues round-trip with any BCF-compatible tool. |
| DXF | 2D → BIM: floor plan becomes IFC walls + spaces. |
| Calibrated takeoff and markup. | |
| Point clouds | PCD, XYZ, LAS, LAZ — as-built comparison and reference. |
| Meshes | OBJ, STL, PLY, glTF — reference overlay only. |
| GIS | GeoJSON vectors, GeoTIFF DEM terrain — georeferenced site context. |
| Excel / CSV | Generic import into any module. |
| RVT | Optional and paid, via Autodesk APS, behind a feature flag. Never assume RVT can be read offline. |
| What | Where from |
|---|---|
| IFC | /publish — the edited model, GUIDs intact |
| SVG · PDF · DXF | Drawings, sheets, schedules |
| XLSX | QTO, COBie, spaces, schedule, and every Report Center report |
| CSV | Any module register, via /export.csv |
| BCF | /bcf/export |
| Records, contracts, pay apps, WH-347, reports | |
| RESO | /listings/{lid}/reso — MLS data-dictionary export |
| COBie | With Contact, Zone and System — the handover chain into a CMMS |
These stay separate on purpose:
- Geometry streams as
.fragtiles, pre-converted on the server. - Data comes from the API.
The browser never parses full IFC at runtime. This is what lets large models open on a laptop, and it is also why the viewer works offline — the WASM is local and tiles are self-hosted.
The viewer runs fully offline: local WASM, self-hosted tiles, no third-party CDN. The desktop app carries its own storage. Online licence validation against massing.cloud exists but is optional and off by default; the tier recorded locally is authoritative until you turn it on.
DELETE /projects/{id} removes the rows, the geometry and the attachments. It is not a soft delete.
- mass-format.md — the container specification.
- authoring.md — bringing geometry in and editing it.
- drawings.md — what the document set produces.