What is the FMW file format?
An .fmw file is an XML-based ETL (Extract, Transform, Load) workspace created by FME Form (formerly FME Desktop), Safe Software's spatial and data integration platform first released in 1997.
The workspace stores a complete data translation pipeline as a UTF-8 XML document. It defines readers (input data sources and formats), writers (output destinations), transformers (data manipulation steps), connections between components, coordinate system definitions, and run-time parameters. FME supports over 450 spatial and non-spatial formats - GIS, CAD, raster, tabular, and others - making .fmw workspaces widely used in geospatial and data engineering workflows.
The XML root element is <Workspace> with Safe Software namespace declarations. A version attribute records the FME version that created the file. FME Form maintains backward compatibility within its published support window, so older workspaces generally open in newer versions without manual migration.
Workspaces run directly in FME Form (interactively or via command line with fme.exe) or are published to FME Flow (formerly FME Server) for scheduled or event-triggered automated execution. FME Flow treats .fmw files as the primary deployment unit for server-side jobs.
Because .fmw files are plain XML text, they integrate well with Git or SVN version control - diffs between workspace versions are human-readable at the transformer and parameter level.
FME Desktop was rebranded to FME Form in 2023 as part of Safe Software's broader platform restructuring; the .fmw extension remained unchanged.
Security & safety
RISK: MEDIUMFMW workspace files are XML and cannot execute code outside FME. However, they often contain embedded database connection strings, API keys, file paths, and credentials in Published Parameters. Treat FMW files as potentially sensitive configuration files - do not share publicly or commit to public repositories without scrubbing credentials.
Format details
in a nutshellPrograms that open FMW files
Windows1 app
FME Form (formerly FME Desktop)
Paid Open FME Workbench → File → Open Workspace → select the .fmw file. Free 30-day trial available. 
macOS1 app
Linux1 app
FME Form
Paid FME Form is available for Linux (server/headless usage via FME Flow typical; GUI Workbench also available).
FME Flow (server execution)
Paid Upload .fmw workspace to FME Flow; run via web interface or REST API. Not a viewer - requires FME Form to design/edit. Technical details
deep spec| Encoding | UTF-8 XML (plain text) |
| XML root element | <Workspace> with Safe Software namespace declarations |
| Version control | Plain XML enables Git/SVN diff; workspace changes are human-readable at transformer level |
| Format breadth | Supports 450+ spatial and non-spatial data formats via reader/writer definitions in the workspace |
| Core components | Readers, writers, transformers, parameters, connections, coordinate system definitions |
| Backward compatibility | Older workspaces open in newer FME Form within 3-year published support window |
| Server execution | Workspaces publish to FME Flow (formerly FME Server) as the primary deployment unit |
| Command-line execution | fme.exe workspace.fmw runs a workspace non-interactively from the command line |
| Typical file size | 10 KB-10 MB (complex workspaces with many transformers and embedded parameters) |
| Rebranding | FME Desktop renamed to FME Form in 2023; .fmw file extension unchanged |
| Related formats | .fmwt (workspace template), .fms (FME script), .fmf (FME feature store) |
| Self-referential | FME Workspace Reader can read .fmw metadata as data features within FME itself |
| Released | 1997 (FME - Feature Manipulation Engine, Safe Software) |
| Latest version | FME Form 2026.0 (backward-compatible format) |
| Specification | docs.safe.com |
FMW conversions
Community Q&A
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