Category: SQL Server

by Jesus Zambrano 2026-04-22

Expose your database as an API in minutes (Data API Builder for Azure Databases)

One of the biggest bottlenecks in application development is API creation. Even though there are very powerful frameworks, they still require time, maintenance, and an additional layer of complexity.

This is where Data API Builder (DAB) comes into play — a tool that shifts the paradigm: instead of building an API on top of the database, it generates it directly from it.

What is Data API Builder?

Data API Builder is an open‑source tool from Microsoft designed to automatically expose databases as REST and GraphQL APIs.

It is specifically designed to work with:

Azure SQL Database
SQL Server
PostgreSQL
Azure Cosmos DB

Its main advantage is that it eliminates the need to build a traditional backend for many use cases.

What problem does it solve?

In a typical scenario:

You have a database
You need an API
You build a backend (Node, .NET, Python…)
You add endpoints, security, validations…

With DAB, that flow is simplified:

You have a database
You define a configuration
You already have an API

This reduces:

Development time
Maintenance costs
Architectural complexity

Simplified architecture

Without DAB:

Frontend → Backend → Database

With DAB:

Frontend → Data API Builder → Database

It removes an entire layer.

How it actually works

Data API Builder acts as an intermediate layer that:

It connects to the database
It interprets the configuration
It generates endpoints dynamically
It applies security rules

All of this through a single configuration file (dab-config.json).

When to choose DAB vs. a traditional backend

Scenario	DAB	Traditional backend
Fast MVP	✅	❌
Simple CRUD	✅	❌
Complex logic	❌	✅
High control	❌	✅
Advanced integrations	❌	✅

Deployment

Requirements

First of all, we need to understand what we’re installing:

.NET Runtime: the environment required to run applications built with .NET. Data API Builder is built on .NET, so it needs this runtime to work.
NuGet: the package manager for .NET. It allows you to download tools and libraries, such as Data API Builder.
Data API Builder (DAB)

1. Install .NET 8 Runtime

Download and install version 8.0.25:

https://dotnet.microsoft.com/en-us/download/dotnet/thank-you/runtime-8.0.25-windows-x64-installer

The following steps are executed in CMD

2. Add the NuGet repository

In some environments, it’s necessary to add NuGet manually:

dotnet nuget add source https://api.nuget.org/v3/index.json -n nuget.org

3. Install Data API Builder

dotnet tool install --global Microsoft.DataApiBuilder

This will install the dab command on your system.

4. Prepare the environment

We create a folder where the API configuration will live:

mkdir C:\dab-demo
cd C:\dab-demo

This folder will contain the dab-config.json file, which defines how the database is exposed.

5. Initialize Data API Builder

dab init --database-type "mssql" ^
  --host-mode "Development" ^
  --connection-string "Server=.\natillas;Database=BlogDemo;User Id=natilla;Password=natilla;TrustServerCertificate=true;Encrypt=true;"

This command:

Connects to SQL Server
Generates the configuration file
Prepares the API

6. Add entities (tables)

dab add Customers --source "dbo.Customers" --permissions "anonymous:*"
dab add Orders --source "dbo.Orders" --permissions "anonymous:*"
dab add OrderItems --source "dbo.OrderItems" --permissions "anonymous:*"

Here we are indicating which tables we want to expose as an API.

The permission anonymous:* allows full access without authentication (for testing only).

7. Start the API

dab start

Available endpoints

Once Data API Builder is running, it automatically exposes several endpoints that allow us to interact with the data in different ways. This is especially useful because, without developing any backend, we already have a complete API with built‑in documentation.

The main generated endpoints are shown below:

REST API: allows querying and manipulating data through HTTP requests. Example with the orders table:
http://localhost:5000/api/Orders

Swagger (OpenAPI): provides a visual interface to explore and test the available endpoints without needing external tools.
http://localhost:5000/swagger

GraphQL: allows performing more flexible queries and obtaining structured data according to the client’s needs.
http://localhost:5000/graphql

These endpoints allow you to quickly verify that the API is working correctly and serve as a foundation for integrations with applications, dashboards, or analytics tools.

What did we just do?

In a few steps we have achieved:

Connect to SQL Server
Generate an API automatically
Expose REST endpoints
Have GraphQL available with zero code

All of this without developing a traditional backend.

Netx steps

Once we have the API running, the next step is to evolve the project toward a more realistic, production‑ready environment.

Real security (roles)

In the example we used open permissions (anonymous:*), which is useful for testing but not suitable for production environments.

Data API Builder allows you to define:

Access roles (for example: anonymous, authenticated)
Entity‑level permissions
Operation‑level restrictions (read, write, etc.)

This makes it possible to control who can access which data and how, while also integrating with authentication systems such as Azure Entra ID.

Deployment in Azure

Once the local setup is validated, the next step is to move the API to the cloud.

A typical deployment would include:

Azure App Service to host Data API Builder
Azure SQL Database as the database
Managed Identity to handle authentication without credentials
Environment variables to configure the connection

This makes it possible to have a fully managed, scalable API that can be accessed from any application.

Conclusion

Data API Builder is a tool that fits perfectly in scenarios where speed and simplicity are key.

It doesn’t replace a full backend, but it does cover a large percentage of cases where what you really need is simply to expose data.

If you work with Azure and databases… it’s definitely worth trying.

Articles in the SQL Server 2025 Series

Jesus Zambrano

I am a data engineer with experience in SQL Server and data analysis. I am certified in database administration and specialized in designing efficient and secure environments for database applications. My approach includes the application of analysis techniques to extract valuable information and support strategic decision making.