GraphQL on Mobile: Apollo vs Relay

Why GraphQL?

No over-fetching. Mobile bandwidth is precious. Request exactly the fields you need for the screen. Great for nested resources.

Flexible. Easy to setup. Good declarative hooks. Massive ecosystem. The default choice for 90% of teams.

Performance first. Uses a compiler to optimize queries at build time. Enforces "Data Masking" (components only see data they ask for).

Both use a normalized cache (IDs). Updates to one screen automatically update others. Relay's store is transaction-based and very robust.

Relay's killer feature. Define data requirements inside the UI component. The parent query stitches them together. Prevents under-fetching bugs.

Update the UI before the server responds. Both support this, but Apollo's API is slightly more intuitive for simple cases.

Apollo is easier. Relay requires buying into a strict framework and build pipeline. Relay is better for massive, changing apps (Facebook scale).