Fabric Apps: building a data app on your Power BI semantic model
Easy Insight Team ·
Fabric Apps is Microsoft's preview platform for building custom web apps with Fabric as the backend. Its data app template queries your Power BI semantic model with DAX, so the app shows the same numbers as your reports. As of November 2026 it needs Fabric capacity and TypeScript skills, and it is not yet available in UK South.
What is Fabric Apps?
Microsoft's Fabric Apps overview describes it as a preview built on the Rayfin SDK, an open-source toolkit and command-line tool. A developer defines the app's data model in TypeScript, and Fabric generates the APIs, handles sign-in and hosts the result.
Each app gets a managed backend inside your Fabric tenant:
- a SQL database in Fabric for the app's own data
- a GraphQL API over that data
- authentication through Microsoft Entra ID, the same sign-in your staff already use for Microsoft 365
- hosting for the app's web pages, updated on each deploy
That is the part worth noticing. The backend work that usually takes the longest in a small internal tool (a database, an API, sign-in, a server to host it) is provided by the platform. What is left is the screens and the business rules.
Fabric Apps is a different thing from Power BI's existing workspace apps and org apps, which package reports and dashboards for an audience. A Fabric App is software you write.
How does a data app use your Power BI semantic model?
Microsoft publishes a data app template aimed at Power BI teams. It connects to a published semantic model and queries it with DAX through the Execute Queries REST API. In practice the app asks the model the same kind of question a report visual asks, so a measure such as gross margin is calculated once, in the model, and both the report and the app use it.
If your measures and relationships are already sound, you can build on them. If they are not, an app will expose the same problems a report does. Our guide to Power BI semantic models covers what a good model needs.
The template is not the only way in. Microsoft's connectors page lists four Fabric data sources, as of November 2026:
| Fabric item | What the app can do |
|---|---|
| Semantic model | Run DAX queries (read) |
| Lakehouse SQL analytics endpoint | Read |
| Warehouse | Read, create, update, delete |
| SQL database in Fabric | Read, create, update, delete |
The write access matters. A report can show that a target was missed. An app can also let the regional manager record why, and save it to a warehouse table the next report reads.
What do you need before you start?
The data app template's prerequisites, as listed on Microsoft Learn in November 2026:
- Node.js 20 or later, and access to Fabric
- a Fabric workspace where you are a Contributor, Member or Admin
- the Fabric Apps (preview) tenant setting switched on by a Fabric administrator
- the Semantic Model Execute Queries REST API tenant setting switched on
- Build and Read permissions on a semantic model hosted on Fabric or Power BI capacity
- the workspace ID and item ID of that semantic model
Microsoft's quickstart also says the workspace must have Fabric capacity assigned. Tenant settings can be scoped to a security group, so a sensible first step is to enable the preview for the two or three people trying it, not the whole organisation.
Is Fabric Apps available in the UK?
This is the first thing a UK business should check. Microsoft's Fabric region availability page, updated in November 2026, lists Fabric App (preview) as not available in UK South. UK West, North Europe and West Europe are not listed as unavailable.
Fabric feature availability follows your tenant's home region, which your Fabric administrator can confirm. Microsoft's suggested workaround is a capacity in a region where the feature is available. Before you do that, check whether your data protection commitments allow the data to be processed outside the UK.
What does it cost?
As of November 2026, Microsoft Learn says Fabric Apps services consume capacity units from the workspace's Fabric capacity. Microsoft has not published a separate price for Fabric Apps, so the cost is the share of capacity your app uses. Our Microsoft Fabric pricing guide covers what each capacity size costs.
Power BI Pro is a moving target. On 28 September 2026, Microsoft's FabCon announcement said Pro and Premium Per User customers "at no additional cost, will also have access to Fabric Apps", up to 1 GB per app. The same post promised app building inside Power BI Desktop, described in plain English, within "the coming weeks". As of 12 November neither appears in the docs: the October 2026 Power BI update does not list them, and the storage page says storage "isn't supported in Power BI Pro workspaces". We covered what else was announced in our FabCon Europe 2026 summary, and Ignite (17 to 20 November) is the next place to look, as our Ignite 2026 watchlist notes. Plan on capacity for now. Our Power BI licensing guide explains how Pro and Fabric capacity differ.
When is an app the right tool instead of a report?
Microsoft's own Power BI guidance on Fabric Apps says apps "complement reports" and that reports remain the core analytics experience. Its overview names the good fits: rapid prototypes, internal tools and dashboards, data exploration, and AI or agent apps that need to keep state. It names the poor fits too: complex multi-step transactions, stored procedures, and any sign-in other than Fabric single sign-on. After deployment, users can only sign in with Microsoft Entra ID, so this is for staff, not customers.
Our rule of thumb, which is opinion rather than Microsoft guidance: if people only need to read and compare numbers, build a report. If they need to act on the numbers, such as entering a forecast, approving an exception or working through a checklist, an app starts to earn its keep. If the tool is really a standalone business system with its own customers, it probably belongs outside Fabric, and our guide to build vs buy for SME software helps with that decision.
How does a build actually go?
The quickstart is short. A developer creates the project from the template with npm create @microsoft/rayfin@latest and --template dataapp, adds the semantic model as a connector, then deploys with npx rayfin up. Microsoft's template ships with prompts and "agent skills" for coding assistants such as GitHub Copilot, including help writing DAX queries and checking the app in a browser.
AI help shortens the typing, not the thinking. Someone still decides what the app is for, who may change what, and how a saved record flows back into reporting. Permissions also need care: by default every member of the workspace can run the app, and workspace roles do not override item-level permissions.
Frequently asked questions
What is Fabric Apps?
Fabric Apps is a Microsoft Fabric preview for building custom web apps with Fabric as the backend. It is built on the open-source Rayfin SDK: developers define data models in TypeScript, and Fabric provides the database, a GraphQL API, Microsoft Entra ID sign-in and hosting.
Can a Fabric App use our existing Power BI semantic model?
Yes. Microsoft's data app template connects to a published semantic model and queries it with DAX through the Execute Queries REST API, so the app uses the same measures as your reports. You need Build and Read permissions on a model hosted on Fabric or Power BI capacity.
Is Fabric Apps available in the UK?
Not everywhere. As of November 2026, Microsoft's region availability page lists Fabric App (preview) as not available in UK South, while UK West is not listed as unavailable. Availability follows your tenant's home region, so check which region your tenant uses before planning a build.
Do we need Fabric capacity, or is Power BI Pro enough?
As of November 2026, Microsoft Learn says the workspace must have Fabric capacity assigned, and apps consume capacity units from it. Microsoft announced on 28 September 2026 that Pro and Premium Per User customers will get Fabric Apps at no additional cost, up to 1 GB per app, but the documentation does not reflect that yet.
Should we replace our Power BI reports with a Fabric App?
No. Microsoft positions Fabric Apps as a complement to reports, not a replacement. Keep reports for reading and comparing numbers, and consider an app when people need to act on the data, such as entering targets, approving items or following a guided workflow.
Thinking about an app on top of your reporting? See how we approach apps, Power BI and Microsoft Fabric and web apps and custom software, or tell us what it needs to do.
Easy Insight is a UK consultancy for AI, web, apps and data — senior specialists only, no juniors.
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