A FileMaker Web Viewer is a layout object that displays web content inside a FileMaker custom app.
At its simplest, it behaves like a small web browser embedded in a FileMaker layout. It can display a website, an online map, a document, or any other content available through a URL.
However, modern Web Viewers can do considerably more. They can contain complete interfaces built with HTML, CSS, and JavaScript and exchange information with FileMaker fields and scripts.
This makes the Web Viewer one of the principal technologies for extending the FileMaker user interface beyond its native layout objects.
Displaying web content inside FileMaker
A Web Viewer is added to a layout in FileMaker Pro. Its web address can be fixed or calculated dynamically using information from the current record.
For example, a Web Viewer might display:
- A customer’s website
- A location in an online mapping service
- A parcel-tracking page
- A document stored on another platform
- An online payment page
- A product or supplier page
- An internal company website
- A page generated by another business application
Because the address can be calculated, the displayed page can change automatically as the user moves from one FileMaker record to another.
More than an embedded browser
The original purpose of the Web Viewer was to display websites without leaving FileMaker. Over time, it evolved into a way of embedding custom web interfaces inside a FileMaker application.
A Web Viewer can display HTML generated directly by a FileMaker calculation using a data: URL. The HTML does not necessarily need to come from a public web server.
Developers can therefore create self-contained components using:
- HTML for structure
- CSS for presentation
- JavaScript for behavior
- FileMaker data for content
This makes it possible to add interface elements that would be difficult or impossible to build using native FileMaker layout objects alone.
What can be built with a Web Viewer?
Common uses include:
- Interactive charts
- Calendars and scheduling interfaces
- Maps and geographical visualizations
- Timelines
- Dashboards
- Organization charts
- Signature interfaces
- Custom navigation components
- Rich text editors
- Image and document viewers
- Drag-and-drop interfaces
- Specialized data visualizations
A developer can also use established JavaScript libraries instead of creating every component from scratch.
The Web Viewer does not replace FileMaker layouts. It extends them where web technologies provide a more appropriate interface.
Communication between FileMaker and JavaScript
FileMaker and the JavaScript running inside a Web Viewer can communicate in both directions.
From FileMaker to JavaScript
The Perform JavaScript in Web Viewer script step allows a FileMaker script to call a JavaScript function inside a named Web Viewer.
FileMaker can pass one or more parameters to that function. JavaScript can then update a chart, display another record, change the interface, or perform another action without reloading the entire Web Viewer.
This script step was introduced with FileMaker 19 and transformed the Web Viewer into a much more capable application component.
From JavaScript to FileMaker
JavaScript can call a FileMaker script using the functions provided by the FileMaker client:
FileMaker.PerformScript()FileMaker.PerformScriptWithOption()
The JavaScript code can pass a parameter to the FileMaker script. That script can then create or update records, perform a find, navigate to another layout, call an API, or initiate any other permitted FileMaker workflow.
For example, an interactive calendar displayed in a Web Viewer could call a FileMaker script when the user creates or moves an event. The FileMaker script would then update the corresponding database record.
A bridge between two environments
The Web Viewer allows developers to combine the respective strengths of FileMaker and web technology.
FileMaker provides:
- Structured data
- Relationships
- Calculations
- Scripts
- Security
- Multi-user access
- Server hosting
- Business workflows
HTML and JavaScript provide:
- Specialized interface components
- Advanced visualizations
- Animation
- Browser-based libraries
- Fine control over presentation
- Interaction models not available as native FileMaker objects
The result remains a FileMaker custom app, but selected parts of its interface can be implemented using the wider web-development ecosystem.
Web Viewer and WebDirect are different
A Web Viewer should not be confused with FileMaker WebDirect.
FileMaker WebDirect makes an entire FileMaker custom app available through a web browser.
A Web Viewer displays web content inside a FileMaker layout.
A Web Viewer can also appear inside an application accessed through WebDirect, but browser security rules create additional restrictions. In particular, JavaScript communication between FileMaker and a Web Viewer in WebDirect is subject to the browser’s same-origin policy.
A Web Viewer solution that works in FileMaker Pro should therefore be tested separately in FileMaker Go and WebDirect.
Where does the Web Viewer run?
The Web Viewer is a client-side layout object.
It is supported in:
- FileMaker Pro
- FileMaker Go
- FileMaker WebDirect, with some differences and restrictions
It is not available in server-side script sessions, the FileMaker Data API, OData, or Custom Web Publishing because those environments do not display FileMaker layouts.
A script executed by the FileMaker Server Script Engine cannot interact with a Web Viewer. It can prepare data that a client later displays, but it has no visible Web Viewer of its own.
Security considerations
A Web Viewer can display external content and execute JavaScript, so it must be treated as part of the application’s security architecture.
Developers should consider:
- Whether the displayed website is trusted
- Which data is passed into HTML or JavaScript
- Whether confidential information is included in a URL
- Which FileMaker scripts JavaScript is allowed to call
- Whether script parameters are validated
- How authentication cookies are handled
- Whether remote libraries can change without notice
- Whether the content requires an internet connection
The option allowing JavaScript to perform FileMaker scripts must be enabled explicitly for the Web Viewer. It should be used only when required.
A FileMaker script called from JavaScript executes with the privileges of the current FileMaker user. It should validate every requested operation rather than assuming the Web Viewer’s content is trustworthy.
Local or remotely hosted content
A Web Viewer interface can obtain its HTML and JavaScript in several ways.
It may be:
- Generated directly by a FileMaker calculation
- Stored in FileMaker fields or containers
- Included in the application as local resources
- Hosted on an internal web server
- Hosted on a public web server
- Loaded from a third-party service
Self-contained content can reduce external dependencies and may continue working without internet access. Remotely hosted content can be updated independently of the FileMaker file and may be easier to maintain across several applications.
The appropriate approach depends on security, offline requirements, application maintenance, and the complexity of the web component.
Web Viewers on FileMaker Go
Web Viewers are particularly useful in FileMaker Go because they can combine FileMaker mobile workflows with touch-oriented web interfaces.
A mobile custom app might use a Web Viewer for signatures, maps, charts, image annotation, or another specialized interaction.
Developers must still account for device performance, screen size, offline access, and differences between the web-rendering environments used on desktop and mobile devices.
Web Viewer expertise from fmcloud.fm
Building a useful Web Viewer involves more than placing a website inside a FileMaker layout.
The interaction between FileMaker context, JavaScript, scripts, security, hosting, and different clients must be designed as a complete system.
At fmcloud.fm, our expertise covers FileMaker development, JavaScript integration, APIs, FileMaker Go, WebDirect, and hosted application architecture. We can help create new Web Viewer components, modernize existing integrations, and diagnose interfaces that behave differently across FileMaker Pro, Go, and WebDirect.
When remote content or services are involved, we can also help design the secure communication between the Web Viewer, FileMaker Server, and external systems.
