GraphQL vs traditional rest api - which one to use and when

Choosing between GraphQL and REST for your API design depends on the specific requirements of your application, the nature of the data interactions, and the development resources available. Both approaches have their strengths and weaknesses, and understanding these can help you make an informed decision.

When to Use GraphQL

1. Complex Data Relationships: If your application involves complex data structures with many interrelated entities, GraphQL allows clients to fetch related data in a single request. This is particularly useful for applications like social networks, e-commerce platforms, or any system where the data is heavily interconnected.

2. Need for Flexibility in Client Requests: GraphQL lets clients specify exactly what data they need, which can reduce the amount of data transferred over the network. This is beneficial for mobile applications or web applications that operate over slow network connections.

3. Rapid Development and Iteration: With GraphQL, adding new fields and types to your API doesn’t affect existing queries. This flexibility facilitates quicker frontend development, as changes can be made on the backend without requiring adjustments in the frontend code, as long as the changes are additive.

4. Real-time Data with Subscriptions: GraphQL supports real-time updates through subscriptions, allowing clients to maintain a consistent state by receiving data in real-time. This is ideal for applications that require instant updates, such as messaging apps or live feeds.

5. Versioning Challenges: Unlike REST, GraphQL avoids the need for versioning (e.g., /v1, /v2 in the API path) since new features or changes in data requirements can be managed without impacting existing queries.

When to Use REST

1. Simplicity and Standardization: REST APIs follow a standard, well-understood convention over HTTP. For simple applications or when your team is more familiar with RESTful principles, REST can be easier to implement, understand, and debug.

2. Caching: HTTP caching in REST is straightforward and well-supported by existing infrastructure (like CDNs and reverse proxies). If your application benefits significantly from caching immutable or slowly changing data, REST might be more advantageous.

3. Code on Demand: REST can deliver code to clients (e.g., JavaScript) that can be executed, offering flexibility in how clients interact with your service. This can be useful in certain applications where client behavior needs to be dynamically updated.

4. Uniform Interface and Statelessness: If these REST principles align well with your application’s architecture, using REST can lead to a more coherent and predictable system. Applications that perform standard CRUD (Create, Read, Update, Delete) operations often fit well with REST’s architectural style.

5. Bandwidth and Resources: If the API consumers do not require the flexibility to fetch different sets of data in a single request and your API serves relatively straightforward responses, REST might be more efficient in terms of development and bandwidth, especially if the API responses are optimized and not overly verbose.

In short, Use GraphQL when you need high flexibility in client queries, have complex data relationships, need real-time data updates, or want to avoid versioning issues. Use REST when simplicity, statelessness, uniform interfaces, and caching are priorities, or if your data access patterns are relatively simple and can be easily expressed in a URL hierarchy.