Driver 01
Over-fetching and round trips
Mobile screens that need many sequential REST calls to assemble one view.
Migration playbook: REST APIs → GraphQL / gRPC
REST to GraphQL and gRPC API migration
Reduce over-fetching and serialization overhead by putting GraphQL in front of UI clients and using gRPC between internal services.
Migration drivers
Why teams make this move
Driver 02
Schema drift
API documentation drifting out of sync with the responses the backend actually returns.
Driver 03
JSON serialization overhead
CPU spent serializing and parsing large JSON payloads between internal services.
Execution sequence
How the migration runs
Each phase ends with a check you can verify — data parity, error rates, latency — and the rollback path is agreed before any traffic moves.
- 01Phase
Schemas and Protobuf contracts
Defining GraphQL schemas and Protocol Buffer contracts as the single source of truth.
- 02Phase
Backend-for-frontend gateway
Deploying a GraphQL gateway (for example Apollo Router) over the existing REST services.
- 03Phase
gRPC for internal calls
Moving high-throughput service-to-service calls to gRPC.
- 04Phase
Client generation and deprecation
Generating typed clients and retiring REST endpoints once their traffic has moved.
Risk prevention
Pitfalls that derail this migration
Risk 01
Unbounded query depth
No complexity or depth limits, which leaves the database open to expensive queries.
Risk 02
N+1 queries
Resolvers without DataLoader batching, firing one SQL query per item.
Risk 03
gRPC from browsers
Calling gRPC from browsers without gRPC-Web or a translating proxy such as Envoy.
Before and after
What we measure
We take a baseline before any change and report the same numbers after cutover, from your own tools. They are the evidence of whether the migration worked — not figures promised in advance.
- Payload size
- Bytes transferred per mobile screen, before and after
- Calls per screen
- Network requests needed to render key screens
- p95 latency
- Service-to-service calls moved to gRPC
Questions
Frequently asked migration questions
Use GraphQL for web and mobile clients that need flexible, declarative data fetching. Use gRPC for high-throughput, low-latency communication between internal services.
GraphQL avoids breaking version URLs (v1, v2) by deprecating fields with @deprecated and evolving the schema additively.
Rehearse the cutover before the real one
Tell us about your data volume, traffic and timeline. An engineer will reply within one business day to set up a call about the migration plan and its rollback path.