Microsoft put Fabric Apps and the Rayfin SDK into public preview on June 2, 2026 at Build. I migrated our BIChart Migration calculator to Rayfin and Fabric Apps and was blown away how fast and easy it was.
With a crystal clear vision of what I wanted, I let Copilot scaffold the frontend, then the Rayfin backend, shipped to my Fabric workspace.
Rayfin is Object-Relational Mapper (ORM) and API designed for AI builds
Rayfin is an SDK and CLI, that defines a Fabric App’s data model in TypeScript. From those model definitions it generates the APIs, provisions the backing SQL database, wires up Entra ID authentication, and hosts the application inside a Fabric workspace. You scaffold with npm create @microsoft/rayfin@latest and deploy with npx rayfin up.
The part that matters for anyone already invested in Fabric is where the data lands. Application writes go to OneLake by design. That means the transactional data an app collects is immediately available to Power BI, notebooks, and pipelines without building a separate extract path. For teams who have spent years moving operational data into the warehouse after the fact, that is a real change in sequencing.
Lesson learned: Evaluate Rayfin as a data placement decision first and an application framework second. The framework is competent. The OneLake routing is the part that changes your architecture.
Easy Builds with Maintenance Questions
The agent-first framing makes experienced builders uneasy, and the discomfort is legitimate. If an agent scaffolds the schema, generates the API surface, and produces the frontend, the question of who owns the design decisions gets fuzzy. The builder’s experience, approach and iterations over time has a dramatic influence over the work product.
We have taken a careful and deliberate approach to employing Fabric Apps. There are many examples and categories of products that exist which are analytical, require data modeling, and require persistence.
- Compensation management is another one, often bolted onto CRMs and ERPs.
- Complex simulator and assessments are near and dear to me, having built hundreds of calculator, survey, and assessment tools over the years.
Where Rayfin and Fabric Apps work at BIChart
Our production use of Fabric Apps has been narrow but the results are amazing. The pattern is an application that reads governed data already in Fabric from our CRM, renders a rich interactive report against it, and persists user input back to a durable store. Read, present, write back, retain all captured in one nice package that we use with prospects every week.
For that shape of application, Rayfin has performed well over the last couple of months with regular changes. Schema updates, frontend revisions, and redeploys have been routine. The CLI workflow is the same for new apps and for later schema and frontend changes, which keeps iteration cheap. Nothing about it has felt like preview software so far.
Finding Use Cases: Locate Excel Processes
Enterprises still originate new processes in Excel. A spreadsheet appears because someone needs to capture data that no system captures, it circulates, decisions get made from it, and eventually it becomes load bearing infrastructure sitting on a file share with no lineage, no access control, and one owner who understands it.
That is the workload Fabric Apps is genuinely good at absorbing when the impact is great enough. The worst thing that could happen is Excel marts turning into a Fabric App deluge; at a higher price.
The ability to graduate a shadow process into a governed one without building an application platform is exciting.
What to Watch Operationally with Rayfin and Fabric Apps
Preview status is not a formality here. There is no production SLA, so a failure in the Rayfin runtime carries no guaranteed response time. CLI commands and TypeScript decorators may change before general availability, and no GA date has been announced. The workload is also disabled by default and requires a Fabric admin to enable it.
Where This Leaves Us
At this stage, the initial excitement of “art of the possible” has tapered off for now. Ongoing community interest, upcoming conferences, and community promotion will drive broader adoption of Fabric Apps as it moves along a path toward general availability.
