Relay vs Apollo: Choosing a GraphQL Client

Both Relay and Apollo are production-grade GraphQL clients for React. But they have fundamentally different philosophies. After using both extensively, here's how they compare.

Philosophy

Apollo is flexible and approachable. It works with any GraphQL API, requires minimal setup, and lets you structure queries however you want. It's the "easy to start" choice.

Relay is opinionated and optimized. It requires a Relay-compliant schema (Node interface, connections, global IDs), enforces colocated fragments, and runs a compiler. It's the "scales to Facebook" choice.

Data Fetching

Apollo uses hooks with inline queries:

const { data, loading } = useQuery(gql`
  query Posts {
    posts(first: 10) {
      id
      title
      author {
        name
      }
    }
  }
`);

Relay colocates fragments with components:

// PostList.tsx
const query = graphql`
  query PostListQuery {
    posts(first: 10) {
      edges {
        node {
          ...PostCard_post
        }
      }
    }
  }
`;

// PostCard.tsx
const fragment = graphql`
  fragment PostCard_post on Post {
    id
    title
    author {
      name
    }
  }
`;

The Relay approach means each component declares exactly what data it needs. The compiler merges fragments into optimal queries — no over-fetching, no manual optimization.

Caching

Apollo: Normalized cache with manual cache updates. Works well until you have complex relationships or optimistic updates, then you're writing cache manipulation code.

Relay: Normalized store with automatic garbage collection. The compiler knows every component's data requirements, so cache invalidation is precise. Optimistic updates use optimisticResponse with automatic rollback.

Performance at Scale

This is where Relay pulls ahead:

• Compiled queries: The Relay compiler pre-processes queries at build time. No runtime parsing of GraphQL strings.

• Incremental data delivery: @defer and @stream directives work out of the box.

• Automatic pagination: usePaginationFragment handles cursor-based pagination with connection metadata.

• Render-as-you-fetch: usePreloadedQuery starts fetching before the component mounts.

Developer Experience

Apollo wins on:

• Getting started (5 minutes to first query)

• Schema flexibility (works with any GraphQL API)

• DevTools (excellent browser extension)

• Documentation and community size

Relay wins on:

• Compile-time safety (type errors for missing fields)

• Colocated data requirements (no prop drilling data)

• Automatic query optimization (the compiler merges fragments)

• Consistent patterns (one way to do things)

When to Choose Which

Choose Apollo when:

• Building a prototype or small app

• Working with third-party GraphQL APIs you don't control

• Team is new to GraphQL

• Schema doesn't follow Relay conventions

Choose Relay when:

• Building a large, data-heavy application

• You control the GraphQL schema

• Team is comfortable with more upfront complexity

• Performance at scale matters (many components, deep data trees)

For this blog, we use Relay. The upfront investment in schema compliance and fragment colocation pays dividends as the app grows — every component is self-contained, queries are optimized automatically, and pagination just works.