What is a REST API?
REST API stands for Representational State Transfer API. It's an interface that lets two computer systems exchange information over the internet using a standardized set of rules. Think of it as a waiter in a restaurant: you (the client) make a request, the waiter takes it to the kitchen (the server), and brings back what you ordered (the data).
REST APIs have become the standard way for web applications to communicate with each other. When you're scraping data, REST APIs are often the cleanest way to get structured information without parsing messy HTML.
How REST APIs work
REST APIs use HTTP protocols, the same system your web browser uses to load websites. You send a request to a specific URL (called an endpoint), and the server sends back a response, usually in JSON or XML format.
Here's what happens when you call a REST API:
1. You send an HTTP request to a specific endpoint, like https://api.example.com/products
2. The server processes your request
3. The server sends back a structured response with the data you asked for
4. You parse that data and use it however you need
The beauty of REST APIs is that the client and server don't need to know anything about each other's internal workings. You just need the endpoint URL and the expected format. This makes REST APIs perfect for web scraping because you can pull data without understanding the entire backend system.
Core principles of REST
REST APIs follow six architectural principles that make them reliable and scalable:
Client-server separation: The client and server operate independently. The server can update its code without breaking your scraper, as long as the API format stays consistent.
Statelessness: Each request contains everything the server needs to understand it. The server doesn't remember previous requests. This means you can run multiple scraping jobs in parallel without them interfering with each other.
Uniform interface: All REST APIs use the same HTTP methods (GET, POST, PUT, DELETE) in predictable ways. Once you learn how one REST API works, others follow similar patterns.
Cacheable data: Responses can be cached to reduce server load. This helps you avoid making duplicate requests for the same data.
Layered architecture: You might talk to a load balancer, which talks to the actual server. You don't need to know or care about these layers.
Code on demand (optional): The server can send executable code to extend functionality, though this is rarely used in practice.
REST API methods for web scraping
REST APIs use standard HTTP methods that correspond to different actions:
GET: Retrieves data without changing anything. This is what you'll use most often for web scraping. For example, GET /products/123 returns information about product 123.
POST: Creates new resources or submits complex queries. Some APIs use POST for advanced search filters that don't fit neatly in a URL.
PUT: Replaces an entire resource with new data. Less common in scraping scenarios.
PATCH: Updates part of a resource. Also less common for scraping.
DELETE: Removes a resource. You probably won't need this for scraping.
For most web scraping projects, you'll stick with GET requests to pull data and occasionally POST for complex queries.
Why REST APIs matter for web scraping
REST APIs offer major advantages over traditional HTML scraping:
Structured data: You get clean JSON or XML instead of parsing HTML tags. No more hunting through div classes or dealing with layout changes.
Official access: Many platforms provide REST APIs as the legitimate way to access their data. This is more ethical and sustainable than scraping HTML.
Better performance: You only request the data you need instead of downloading entire web pages with images, CSS, and JavaScript.
Clear limits: APIs typically document their rate limits and authentication requirements upfront, so you know exactly what you can do.
Stability: APIs change less frequently than website layouts. Your scraper won't break every time a site redesigns.
Multiple sources: You can easily combine data from different APIs since they all use similar patterns.
REST API vs other options
REST isn't the only API style, but it's usually the best choice for web scraping:
REST vs GraphQL: GraphQL lets you request exactly the fields you want in one query. REST requires multiple endpoints for different data. GraphQL is more flexible but also more complex to implement.
REST vs SOAP: SOAP is an older protocol that's more rigid and verbose. REST is simpler and faster for most use cases.
REST vs gRPC: gRPC is designed for high-performance internal services. REST is better for public APIs and web scraping because it works with standard HTTP.
Real-world REST API examples
You'll find REST APIs everywhere:
Twitter API: Pulls tweets, user profiles, and engagement metrics
OpenWeatherMap: Gets current weather and forecasts for any location
Shopify API: Accesses product catalogs, inventory, and order data
Google Maps API: Retrieves location data, distances, and directions
Stripe API: Manages payment and transaction information
These APIs all follow REST principles, which means once you understand the pattern, you can work with any of them.
