What is GraphQL?
Explore the fundamental principles of GraphQL, its advantages over REST, and when to choose it for your projects.
What is GraphQL? is a free GraphQL APIs with Spring Boot lesson on CoddyKit — lesson 1 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the GraphQL APIs with Spring Boot learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
Meet GraphQL: A New Way to API
Wish an API gave you exactly what you asked for? GraphQL is a query language for APIs that lets clients request precisely the data they need.
REST's Challenge: Over-fetching
REST endpoints return a fixed shape, so you hit over-fetching — asking for a user’s name but downloading their whole profile, wasting bandwidth.
REST's Challenge: Under-fetching
The flip side is under-fetching: one endpoint isn’t enough, so you chain calls for users, then posts, then comments — many round trips that slow you down.
GraphQL: One Request, Exact Data
GraphQL solves both: clients ask for exactly the fields they need from a single endpoint, so you get fewer requests and leaner data transfer.
The Blueprint: GraphQL Schema
At the heart of every GraphQL API is its schema — the contract. It defines every type clients can query and how they relate, written in SDL.
Building Blocks: Types & Fields
Types are defined in SDL. Here a User has id, name, and email fields; the ! marks a field as non-nullable.
Asking for Data: GraphQL Queries
A query is how a client asks for data. It mirrors the shape you want, fetching only the fields you list — even from nested objects.
Your First GraphQL Query
Here’s a simple query: ask only for id and name, and that’s all the server returns for the user with id 1. Nothing extra.
Why Choose GraphQL?
Why pick GraphQL? Efficient fetching, a strongly typed schema that prevents errors, painless API evolution, and great tooling like GraphiQL.
When is GraphQL the Right Choice?
GraphQL shines with complex, interconnected data, multiple client platforms on one API, microservice gateways, and fast frontend iteration.
Check Your Understanding
Which of the following is a primary advantage of GraphQL over traditional REST APIs?
GraphQL: A Powerful API Tool
You’ve got the fundamentals: GraphQL kills over- and under-fetching, the schema is the contract, and queries request exactly what you want. Spring Boot next.
Frequently asked questions
Is the “What is GraphQL?” lesson free?
Yes — the full text of “What is GraphQL?” is free to read here on the web, and the GraphQL APIs with Spring Boot course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the GraphQL APIs with Spring Boot course, upgrade to CoddyKit PRO.
What will I learn in “What is GraphQL?”?
Explore the fundamental principles of GraphQL, its advantages over REST, and when to choose it for your projects. You practise GraphQL APIs with Spring Boot with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start GraphQL APIs with Spring Boot?
No prior experience is required. GraphQL APIs with Spring Boot on CoddyKit is structured for beginners through advanced learners; this is — lesson 1 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “What is GraphQL?” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this GraphQL APIs with Spring Boot lesson?
Yes. Every GraphQL APIs with Spring Boot lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.