Simplifier runs on Firely .NET SDK 6
Simplifier has moved to Firely .NET SDK 6 across the platform. Forge made the same move in 2026.2.0, and Firely Terminal will follow. Moving to SDK 6 also gives us a faster foundation to build on. We expect to deliver performance gains from it in future releases.
What SDK 6 means for validation and Quality Control
The legacy validator is deprecated. All validation and Quality Control now run on the Firely validator, which means two things for your projects.
Expect more findings. The validator catches more than it did before, and issues that stayed hidden in your projects will now surface. Run Quality Control after this release and review the results. Most new errors point at something real in your resources.
If you use custom quality control rules. The SDK 6 parsers accept a much wider range of input. Files with an .xml or .json extension that are not FHIR resources can now be parsed, treated as resources, and handed to the validator. That produces errors on files that were previously skipped. Parsing is reported as its own step in the results, so you can see directly which file failed to parse and why.
If you see unexpected errors on files you do not consider FHIR resources, narrow the scope of your rules. Quality Control offers three ways to do this, and you can combine them:
- File filters select files by globbing pattern, including exclusions such as
"!package.json". - FHIRPath filters keep only the resources for which a FHIRPath statement is true.
- Category filters select a group such as
Conformance,Terminology,Instance,ProfileorExtension, or a specific resource type. The Generic properties page in the Quality Control documentation has the full reference with examples.
We will keep improving the validator and Quality Control, including a better overview of the results.
More complete resource rendering
Your resources say more than the rendering used to show. Besides a list of bug fixes, these enhancements went into rendering:
- Support for the suppression extension in rendering. Profiles you build with the suppression extension in Forge 2026.2.0 now render correctly in Simplifier and in your Implementation Guides.
- The must support flag from
elementdefinition-type-must-supportis now rendered. - The
valueset-deprecatedextension is now visible in ValueSet rendering.
Other features
IntelliSense for page links. Typing
{{pagelink:or{{page:in the Implementation Guide editor now suggests the topics of your guide pages, filtering the list as you type. Linking by topic is more robust than linking by filepath: the link keeps working when you move or rename a page, and when the guide is exported or copied. You choose what it suggests from the IntelliSense menu in the editor toolbar, which now has two sections. Under Resources you pick whether resources are suggested by canonical URL, by name, or by filepath. Under Pages you pick whether pages are suggested by filepath or by topic. Read more about rendering FHIR resources in your guideSide-by-side diff of any two files. Until now you could only diff two versions of the same file from the
Historytab. The new Compare menu on resource pages and package file pages lets you diff any two files against each other: set one file as A, browse to another file, set it as B, and hit compare. Your selection is remembered in the browser while you navigate, so the two files can live in different projects, different packages, or different versions of the same package. Read more about comparing two files
Documentation in one place
Simplifier documentation has been unified on docs.fire.ly, replacing the pages that were scattered across simplifier.net. FQL documentation now covers inline parameters, and what Bake and Quality Control currently implement for categorization is documented.
We also expanded the Firely Terminal documentation, which now covers running Firely Terminal in your CI/CD pipeline in much more depth. Two new pages walk through it end to end: automating quality control shows how to validate your FHIR project on every push or pull request and automating Simplifier Sync shows how to keep a Simplifier project in sync with your repository automatically.
The new features page is also live.
You can find the full release notes in the documentation.
If you have questions or ideas for future developments, do not hesitate to reach out to the Simplifier team. We would love to hear your feedback.
Ardon