The Claris FileMaker Data Migration Tool, often abbreviated as DMT, is a command-line utility that transfers data from one FileMaker file into a newer version of the same custom app.
Its principal purpose is to simplify the deployment of application updates.
A FileMaker custom app contains both its structure and its data. This is convenient for everyday use, but it creates a particular challenge during development: while users continue adding records to the production file, developers may be modifying layouts, scripts, fields, relationships, and other elements in a separate development copy.
When the new version is ready, the latest production data must be transferred into the updated application. The Data Migration Tool automates this process.
How Does Data Migration Work?
A typical migration involves three files:
- the source file, containing the current production data;
- a clone of the new version, containing the updated structure but no records;
- the target file, created by the tool with the new structure and migrated production data.
The tool transfers the records from the source file into the clone while preserving the layouts, scripts, calculations, themes, relationships, and other development work contained in the new version.
The result is an updated FileMaker custom app containing the most recent production data.
Why Not Import the Records Manually?
Without the Data Migration Tool, a developer would have to import data one table at a time.
For a complex application, this can involve many tables and require careful field mapping, import order, serial-number adjustments, account management, and repeated verification. The process is time-consuming and creates opportunities for mistakes.
The Data Migration Tool handles the complete file in a single operation. It automatically matches tables and fields using their names and internal identifiers.
It can also migrate elements that ordinary record imports do not handle easily, including:
- user accounts;
- custom value lists;
- serial-number settings.
This makes the deployment process faster, more repeatable, and less dependent on manual operations.
Reducing Deployment Downtime
The Data Migration Tool is particularly valuable for production applications that cannot remain unavailable for long periods.
Most development and testing can take place before the deployment. When the new version is ready, the production file is closed, its latest data is migrated, and the resulting file is placed into service.
The application must still be taken offline during the migration, but automating the transfer can considerably reduce the maintenance window compared with importing every table manually.
The exact duration depends on the quantity of data, number of files, containers, storage performance, and complexity of the application.
Supporting a Professional Development Workflow
The Data Migration Tool makes it easier to maintain separate development, testing, acceptance, and production environments.
Developers can work on a copy of the application without modifying the live production file. The new version can be reviewed and tested while users continue working normally.
Once approved, the DMT combines:
- the latest application structure from development;
- the latest records and accounts from production.
This separation is an important part of professional FileMaker development. It reduces the risks associated with making structural changes directly in a live application.
What Does the Tool Migrate?
The Data Migration Tool is designed to migrate record data and user accounts between compatible FileMaker files.
It can also handle custom value lists and serial-number settings according to the selected migration options.
The updated structure itself does not come from the production file. It comes from the clone supplied as the migration target. This means that new layouts, scripts, fields, themes, and calculations created during development remain in the resulting application.
The tool applies matching rules to determine how source tables and fields correspond to those in the clone. A migration should therefore always be reviewed, particularly when tables, fields, privilege sets, or value lists have been renamed or substantially reorganized.
What About Persistent Data?
FileMaker 2026 introduced the persistent data store, which allows a custom app to retain configuration values and resources outside its ordinary record data. These entries may include application settings, version information, shared script data, AI prompts, or resources used by web viewers. Persistent data is included when a FileMaker file is cloned, but the Data Migration Tool does not copy persistent data from the source file because it is not considered record data. The resulting target therefore retains the persistent data contained in the new clone rather than the values stored in the production source file. Developers must take this into account during deployment: if production-specific persistent values need to be preserved, they should be exported, recreated, or transferred through a separate process.
What About Container Data?
Container data stored inside the FileMaker file is migrated with the other records.
Externally stored container files require additional consideration. The Data Migration Tool preserves their references but does not copy the external files themselves. The resulting database must retain the correct relationship to the external container directories.
This is one reason why data migration should be planned and tested rather than treated as a simple file-copying operation.
Data Migration Is Not Data Conversion
Despite its name, the DMT is not a general-purpose tool for converting Excel, SQL, or other external databases into FileMaker.
It is designed specifically to transfer data between compatible FileMaker .fmp12 files, usually between two versions of the same custom app.
For importing information from another system, FileMaker imports, ODBC, OData, the Data API, or a purpose-built migration process may be more appropriate.
Can the Process Be Automated?
Yes. Because the Data Migration Tool runs from the command line, it can be integrated into deployment scripts and automated workflows.
A controlled process can close the production database, perform the migration, preserve the original file, place the new version in the correct location, reopen it, and generate logs for verification.
Automation is particularly valuable for developers who maintain the same FileMaker product for multiple customers or deploy frequent application updates.
However, automated migration should include backups, validation, error handling, and a tested rollback procedure. A successful command does not replace functional testing of the resulting application.
Using the Data Migration Tool Remotely with OttoFMS
Running the Data Migration Tool directly normally requires local or command-line access to the computer hosting FileMaker Server. This is not always available or desirable, particularly with a managed hosting service.
OttoFMS removes this requirement. It provides a web interface and deployment workflow that can run the complete migration directly on the server.
A developer can upload the new version of a FileMaker app and deploy it using the current production data without manually:
- accessing the server’s operating system;
- installing or running command-line tools;
- downloading the production database;
- performing the migration locally;
- uploading the migrated file again.
OttoFMS manages the server-side workflow and uses the FileMaker Data Migration Tool to produce the updated application. This can make deployments faster while avoiding the transfer of large database files over the internet.
OttoFMS is free and fully compatible with fmcloud.fm.
Customers can activate it directly from their my.fmcloud.fm console. Once enabled, OttoFMS runs alongside the FileMaker Server instance and makes professional remote deployment possible without local access to the server.
This is particularly useful for FileMaker developers maintaining customer applications hosted on fmcloud.fm. They can use a modern development, testing, and production workflow while the underlying server infrastructure remains securely managed by fmcloud.fm.
Data Migration Expertise at fmcloud.fm
fmcloud.fm hosts FileMaker custom apps that range from small internal databases to business-critical multi-file systems.
Our team can help customers and developers prepare and execute controlled migrations, verify backups, reduce deployment downtime, and restore the previous version if an unexpected problem occurs.
Because OttoFMS can be activated directly on an fmcloud.fm instance, developers do not need command-line access to benefit from the Data Migration Tool. They can manage deployments remotely while fmcloud.fm continues to operate and secure the underlying FileMaker Server environment.
For complex applications, the most important work often happens before the migration begins: checking field and table mappings, privilege sets, external containers, encryption, dependencies between files, and the behavior of the updated solution.
Conclusion
The FileMaker Data Migration Tool transfers current production data into a newer version of a FileMaker custom app.
It allows developers to update layouts, scripts, fields, relationships, and other application components separately from the live production data, then combine the two during deployment.
Compared with manual imports, it offers several important benefits:
- migration of all tables in one operation;
- automatic matching of tables and fields;
- preservation of user accounts and serial numbers;
- fewer manual steps and opportunities for error;
- shorter and more predictable deployment windows;
- better separation between development and production.
With the free OttoFMS platform, the entire process can also be performed remotely without local access to the FileMaker Server machine. OttoFMS is fully supported by fmcloud.fm and can be activated directly from the my.fmcloud.fm customer console.
For any FileMaker application that continues to evolve while users create live data, the Data Migration Tool, either directly or through OttoFMS, is an essential component of a professional deployment workflow.
