Rayfin: Define a Full App Backend in TypeScript and Ship It to Microsoft Fabric
Last Updated on August 3, 2026 by Editorial Team
Author(s): Dave R – Microsoft Azure & AI MVP☁️
Originally published on Towards AI.
How an open source SDK turns a set of TypeScript classes into a database, an API, authentication, and hosting, all running as governed services inside Microsoft Fabric.
This article explains how Rayfin works, from the TypeScript you write to the services that run in Microsoft Fabric. Rayfin is an open source SDK and CLI that lets you define an application backend, including its database, access policies, APIs, and server-side logic, entirely in code, then deploy it to Fabric with a single command. I will walk through the programming model, the decorators that turn classes into tables, the CLI workflow, how connectors reach existing data, and how the whole application lands as a governed Fabric artifact.
After the introduction, the article explains the core Rayfin flow: developers author backend definitions in TypeScript, use decorators to turn classes into data models and access policies, and then run the Rayfin CLI to deploy the result into Microsoft Fabric where it becomes managed services (database, storage in OneLake, authentication, APIs, and hosting). It details how the programming model compiles entity decorators into database schema and enforced authorization on every request, how Rayfin detects model changes and performs migrations with guardrails, and how the CLI supports scaffolding, local development, one-command deploys, and promoting the same app across workspaces (dev/staging/production). The piece also covers deployment configuration via YAML (including current SQL support and planned Postgres), the use of Fabric identity through Microsoft Entra, connectors for importing existing data into typed classes, and server-side TypeScript functions packaged as Fabric functions for secure execution. It highlights templates and extensibility (including the Data App template that builds apps directly on semantic models), why Fabric is the deployment target for integrated governance and OneLake data sharing, and how broader builders (including browser-based agentic builders) can create governed apps without requiring an IDE. Finally, it outlines the roadmap horizons and cautions that the preview-stage CLI/decorators may change, then closes with guidance for getting started and prototyping early.
Read the full blog for free on Medium.
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