Learn GraphQL by doing. Work through the lessons in order and you'll go from your first query against a live API to building and securing your own server — queries, schema design, resolvers, mutations, the N+1 problem, pagination, errors, auth, and consuming it all from a React client. Every lesson is queries you run and code you write.
You can run queries against a live API in the very first lesson with nothing installed. To build your own server (from lesson 5 on) you write JavaScript in Node, and the client lesson uses React — so be comfortable with both. Knowing how HTTP APIs work helps, since GraphQL is an alternative to REST.
Your First Query
Run a GraphQL query against a live public API in minutes — ask for exactly the fields you want, nest into related data, and see why GraphQL returns no more and no less.
The Schema (SDL)
Every GraphQL API is defined by a schema written in SDL. Learn object types, scalar fields, and the special Query type that is the entry point for every read.
Arguments, Variables & Fragments
Make queries dynamic and reusable — pass arguments to fields, supply them safely with variables, rename results with aliases, share field sets with fragments, and branch with directives.
Schema Types: Enums, Lists, Interfaces & Unions
Model richer domains in your schema — fixed choices with enums, polymorphism with interfaces and unions, and reusable shapes with input types.
Building a Server
Stand up your own GraphQL API with Apollo Server in Node — define a schema, wire resolvers, and serve it over HTTP with a built-in sandbox to query it.
Resolvers & Execution
Resolvers are where GraphQL does its work. Understand the four resolver arguments, return data sync or async, and see how nested fields resolve into a result.
Mutations & Input Types
Change data with mutations — define them on the Mutation type, accept structured data with input types, return the updated object, and run several in one request.
Relationships & the N+1 Problem
Connecting types is GraphQL’s superpower and its classic trap. Resolve relationships across types, then fix the N+1 query explosion with batching via DataLoader.
Pagination
Never return an unbounded list. Page results with simple offset/limit, then graduate to the cursor-based Connections pattern that powers infinite scroll at scale.
Errors & Validation
GraphQL validates queries against the schema for free — and returns partial data with a structured errors array. Learn to read it and raise clean, typed errors.
Authentication & Authorization
Secure your API — identify the caller once in the context, then enforce permissions inside resolvers and at the field level, where authorization actually belongs.
Consuming from a Client
Use your API from a React app with Apollo Client — run queries and mutations with hooks, handle loading and errors, and let the normalized cache keep the UI in sync.