What is GraphQL?

GraphQL is a query language and runtime for APIs that lets you ask for exactly the data you need, and get it in a single request. It was created by Facebook to make data fetching more efficient and flexible compared to traditional REST endpoints.

Let's break it down

  • Query language: a way to write a request that looks like the shape of the data you want, similar to writing a sentence.
  • Runtime for APIs: the server side that understands those queries, fetches the data, and returns it.
  • Ask for exactly the data you need: you specify which fields (like name, price, or image) you want, no more and no less.
  • Single request: instead of calling many different URLs to gather pieces of data, one GraphQL query can retrieve everything at once.
  • More efficient and flexible: because you control the shape of the response, you avoid over-fetching (getting unnecessary data) and under-fetching (missing needed data).

Why does it matter?

It saves bandwidth and speeds up apps by delivering only the needed information, reduces the number of round-trips between client and server, and gives front-end developers the power to evolve UI features without waiting for back-end changes.

Where is it used?

  • Mobile and web apps that need fast, responsive interfaces, such as Facebook’s own mobile app.
  • E-commerce platforms (e.g., Shopify) that let merchants query product catalogs, orders, and inventory in one call.
  • Content management systems like Contentful, where editors can fetch articles, images, and metadata together.
  • Public APIs such as GitHub’s GraphQL API, enabling developers to retrieve repositories, issues, and pull requests in a single request.

Good things about it

  • Precise data fetching eliminates over‑ and under-fetching.
  • Single endpoint simplifies network architecture.
  • Strongly typed schema provides clear documentation and auto-completion in IDEs.
  • Clients can evolve independently; adding new fields doesn’t break existing queries.
  • Built-in introspection lets tools automatically explore the API’s capabilities.

Not-so-good things

  • Learning curve: developers must understand schemas, resolvers, and query syntax.
  • Complex caching: because responses can vary widely, standard HTTP caching is less effective.
  • Over-flexibility can lead to overly complex queries that strain the server.
  • Initial setup and tooling can be heavier compared to simple REST endpoints.