Calling REST APIs: How to Connect, Retrieve, and Send Data

Whether you're building with Power Apps, Power Automate, or coding in Visual Studio, understanding how to call REST APIs opens the door to connecting with almost any external system.

🌐 What is a REST API?

A REST (Representational State Transfer) API is a web service that allows you to interact with data using standard HTTP methods like GET, POST, PUT, and DELETE. REST APIs are the backbone of modern web integration—from social media to SharePoint and everything in between.

⚙️ Common Methods

• GET: Retrieve data (e.g., list of documents, user info)
• POST: Send new data (e.g., create a record)
• PUT: Update existing data (e.g., change a status)
• DELETE: Remove data from a system

🔐 Authentication

Most APIs require authentication. This could be in the form of:

• API keys (simple but less secure)
• OAuth 2.0 tokens (common for Microsoft Graph, Google, etc.)
• Bearer tokens passed in request headers

💡 Real-World Use Cases

• Power Automate calling a weather API to enrich a SharePoint list
• Power Apps submitting form data to a custom Azure Function
• Visual Studio app syncing client records via a legal practice management API

🧪 Example: Making a GET Request in Power Automate

1. Add an HTTP action block
2. Method = GET
3. URI = https://api.example.com/data
4. Add headers if needed (Authorization, Content-Type)
5. Parse the JSON response and use it downstream in your flow

🚀 Pro Tip

Use Postman to test your API endpoints before adding them into Power Automate or Visual Studio. It’s a great way to confirm your authentication, headers, and expected responses.

REST APIs make your apps smarter, faster, and more connected. If there's data out there, chances are you can get to it — securely and efficiently.