MDS Files
MDS is the native project file format for MIDAS. The file extension is .mds. An MDS file stores datasets, models, reports, workspace layouts, and other project state in a single file.
Saving and Exporting
There are two ways to save an MDS file.
Save to Browser
File > Save to Browser (Cmd+S / Ctrl+S) saves the project to the browser's local storage (OPFS). Saved projects appear in the launcher's Quick Access section and can be reopened with a click.
Because this uses browser storage, saved projects are only accessible from the same browser and profile. They do not appear in other browsers or on other devices. Clearing browser data will delete saved projects. Export important projects as files for safekeeping.
Export as File
File > Export Project... (Cmd+Shift+S / Ctrl+Shift+S) downloads an .mds file.
Exported MDS files can be shared with other users or kept as backups. To open a received MDS file, drag and drop it onto the launcher screen or use Open File.
About Auto-Save
MIDAS does not perform real-time auto-save. To preserve your work, save explicitly using either method above. Closing the browser tab discards any unsaved changes.
Data Excluded from Saving
Derived Dataset computed results (cache) are not saved in MDS files by default. After opening a project, data is recomputed from parent datasets on demand.
This keeps MDS files small. For Derived Datasets with expensive queries, enable Materialized View to persist the computed data. See Datasets > Materialized View for details.
Digital Signatures
When you save or export an MDS file, it is automatically signed with your signing key. Signatures verify the file creator and detect tampering.
When opening an MDS file, the signer's trust level determines how it is handled:
| Trust Level | Description |
|---|---|
| Official | Signed by the MIDAS operator's key |
| Trusted | Signed by your own key or a registered public key |
| Unknown | Signed by an unregistered signer |
Opening an MDS file from an unknown signer shows a warning. For security, some trained model data is removed. Model definitions are preserved, so you can retrain them.
For managing signing keys, exporting public keys, and registering others' keys, see Managing Signing Keys.
Data Locality
All data processing in MIDAS happens entirely within the browser. Project data is never sent to any external server. Data is stored in the browser's OPFS and IndexedDB, and exported MDS files are simply downloaded to the user's device. Digital signatures use the Web Crypto API (ECDSA P-256); signing keys never leave the browser.
Version Compatibility
MDS files carry a MIDAS version number. When you open an older MDS file in a newer version of MIDAS, migrations are automatically applied.