GraphQL vs. REST: Which Should You Use and When?

Hey there! As an API developer, you may be wondering – which is better for my next project, GraphQL or REST?

Both have their strengths and shortcomings, so it pays to understand them thoroughly. In this guide, I‘ll share my insider knowledge as an API expert to help you pick the right tech for your needs!

A Quick Intro

First, a quick refresher:

REST (REpresentational State Transfer) is an architectural style for building APIs that expose data resources using HTTP methods like GET and POST. It emerged in the 2000s as a popular way to build public-facing APIs.

GraphQL is a newer API query language developed by Facebook that allows clients to request exactly what they need in a single call. It provides more flexibility and efficiency than REST.

Now let‘s get into the details!

Key Differences at a Glance

Here‘s a quick comparison of core features before we dive deeper:

	GraphQL	REST
Data Fetching	Query precisely what you need	Get fixed resources
Requests	Single endpoint	Multiple endpoints
Data Types	Strongly typed	No fixed types
Flexibility	Adaptable queries	Limited flexibility
Caching	Enabled	Difficult
Versioning	Non-breaking changes	Can break clients

As you can see, GraphQL solves some of the long-standing pain points of REST like over and under fetching data. But REST still rules when it comes to simplicity and adoption.

Now let‘s explore each area in depth.

Fetching Data

One of GraphQL‘s biggest advantages is how it lets you retrieve data.

In REST, you can only get fixed resources from predetermined endpoints. There‘s no flexibility in what fields are returned. So you often end up with overfetching – getting more data than needed.

GraphQL instead allows you to request exactly what you need from the server, avoiding over and underfetching. You can pick specific fields, get nested data in one shot, apply filters, pagination – all in a single query.

For example, let‘s say you need to get some data about a user from an API.

A GraphQL query for this could be:

query {
  user(id: 500) {
    name
    age
    address {
      city
      state
    }
  }
}

This allows getting just the user fields you need and nesting the address in it.

In contrast, the REST API would likely return all user fields plus the entire address object – much more data than required!

This querying flexibility makes GraphQL very powerful for apps that need to fetch complex, interlinked data.

Requests and Responses

GraphQL only needs a single endpoint to fetch data. All queries go to that one URL.

Compare this to REST APIs which require separate endpoints for each resource or collection – /users, /posts, /comments and so on.

This means:

Your GraphQL backend only needs one URL handler vs. multiple endpoints in REST.
Frontend code can simply target one API URL rather than many.
Aggregating data from multiple sources is easier – just make one GraphQL request.

The response also varies:

GraphQL always returns JSON with exactly the requested fields.
REST has fixed response structures per endpoint, usually returning entire resources.

So GraphQL minimizes round trips and lets you manipulate responses more granularly.

Strong Typing

GraphQL APIs are built around a strongly typed schema:

type User {
  id: ID
  name: String
  age: Int
}

Requiring defined types for each field provides clarity and acts as documentation. It also enables catching bugs during development like referencing undefined fields.

REST APIs have no such schema. Request and response structures are fixed per endpoint but not formally defined.

So GraphQL brings more structure and safety through its typing system.

Flexibility

GraphQL gives you more flexibility in crafting queries as per your app‘s needs:

Select specific fields, nested objects, apply filters, sorting, and more.
Easily retrieve data from multiple sources in one query.

Compare this to the fixed endpoints and rigid request/response formats in REST.

You work around REST limitations by making multiple API calls from the client and assembling the final dataset on your own.

So GraphQL offers a big flexibility boost overolder REST APIs.

Caching

GraphQL queries are highly cacheable since they have predictable shapes based on the query structure.

REST responses are cacheable too but harder to optimize due to the fixed endpoints returning set resources. There is more likely to be redundant data between requests.

With GraphQL, clients can:

Set unique cache keys based on query shape and variables.
Implement caching libraries like Apollo Cache or relay-runtime-cache.

This makes caching much more efficient especially when fetching overlapping data across queries.

Versioning and Breaking Changes

Changes to GraphQL schemas do not break existing queries as long as the underlying API still supports those fields.

For example, if you add a new address field to a User type, earlier queries still work fine.

With REST, adding or modifying endpoints can break client functionality in a backward incompatible way.

So GraphQL allows you to evolve APIs rapidly without worrying about breaking consumers. This agility helps accelerate development.

Performance

For apps that need to fetch a lot of linked data, GraphQL can deliver significantly better performance than REST:

Faster initial response since only requested fields are returned.
Fewer round trips required to assemble needed data.
Effective caching of query results as schema evolves.

REST performance degrades at scale as you make multiple API calls to gather related data. Response sizes grow despite extracting only portions of the data.

So if performance is critical for your app, GraphQL is likely the better choice.

Learning Curve

GraphQL has a steeper learning curve than REST:

You need to learn the GraphQL query language with its syntax and type system.
Setting up a GraphQL server with schema and resolvers requires learning new frameworks.
Tooling like GraphiQL takes time to master for debugging and documenting your API.

With REST, the simplicity of HTTP requests to access URLs keeps the initial barrier low. The learning curve grows as you work around REST constraints in complex projects.

So for quick prototypes and public APIs, REST may work better. For internal apps with complex data, GraphQL strengths can outweigh the learning overhead.

Tooling and Ecosystem

REST has a much more mature ecosystem with countless libraries and frameworks like Express, Django REST Framework, and Spring Boot. Stable tooling is available for testing, documentation, mocking and more.

GraphQL has solid tools too like Apollo, GraphQL Yoga, and GraphiQL. But the ecosystem is relatively new and still evolving quickly. Some tools may require more customization to suit your needs.

So REST is a safer choice if you want battle-tested tools. GraphQL gives you more cutting-edge capabilities with a less settled ecosystem.

Wrap Up: Key Takeaways

Here are the key points on when to use GraphQL or REST for your API:

Consider GraphQL If You Need:

Flexible data queries with nested retrieval and field selection.
Efficient data loading with fewer round trips.
Rapid product iteration without breaking changes.
High performance even with complex data requirements.

Prefer REST For:

Simple, public-facing APIs with fixed endpoints.
Quick prototyping where simplicity is key.
Leveraging mature tools and stable ecosystem.
Lower learning curve for developers.

You Can Also:

Use GraphQL for internal APIs, REST for external.
Gradually move REST endpoints to GraphQL where it makes sense.
Apply REST principles for overall API design even if using GraphQL.

So in summary:

GraphQL supercharges client-server data fetching but requires more learning.
REST provides a simpler starting point for basic API needs.
Consider your specific goals, constraints and app architecture when deciding.

I hope these insights help you pick the right tech for your next project! Let me know if you have any other questions.