GraphQL Parser

GraphQL is a query language for APIs that lets clients request exactly the data they need. This tool parses and formats GraphQL queries, mutations, and subscriptions with proper indentation and validates syntax.

Specifications

• GraphQL Specification
• GraphQL.org

Common Use Cases

• Format minified GraphQL queries for readability
• Validate query syntax before sending to API
• Debug GraphQL requests from logs or network tools
• Document API queries for team reference

Features

• Parse queries, mutations, and subscriptions
• Format with proper indentation
• Validate GraphQL syntax
• Handle fragments and variables
• Display operation and field structure
• Auto-generate JSON variable template with null values
• Size analysis (original vs minified bytes with savings %)
• Root fields and fragments listing
• Minified view toggle

Examples

query GetUser($id: ID!) {
  user(id: $id) {
    id
    name
    email
    posts {
      title
      createdAt
    }
  }
}

Tips

• GraphQL queries specify exactly which fields to return.
• Use fragments to reuse common field selections.
• Variables ($id) should be passed separately, not interpolated into the query string.

Understanding GraphQL

GraphQL is a query language for APIs developed internally at Facebook in 2012 and open-sourced in 2015. Unlike REST APIs where the server defines each endpoint's response shape, GraphQL lets clients specify exactly which fields they need in a single request, eliminating over-fetching (receiving unused data) and under-fetching (needing multiple round trips).

A GraphQL API exposes a strongly typed schema defining all available types, fields, and relationships. Clients send queries (read data), mutations (write data), or subscriptions (real-time updates via WebSocket). Each operation specifies a selection set of fields, and the response mirrors the exact request shape. Variables allow parameterizing operations without string interpolation, preventing injection attacks and enabling query caching.

Fragments are reusable field selections that reduce duplication across operations. Instead of repeating the same fields in multiple queries, define a fragment once and spread it wherever needed. Inline fragments handle polymorphic types, requesting type-specific fields on union or interface types.

GraphQL has gained broad adoption for client-facing APIs, particularly in mobile applications where bandwidth efficiency matters. Major APIs from GitHub, Shopify, and others offer GraphQL endpoints. The ecosystem includes Apollo Client for state management, GraphQL Code Generator for TypeScript types, and GraphiQL for interactive exploration.

REST and GraphQL take fundamentally different approaches to API design. REST exposes multiple endpoints with fixed response shapes, while GraphQL exposes a single endpoint where clients define exactly what data they need. REST can over-fetch (returning unused fields) or under-fetch (requiring multiple round trips), and GraphQL solves both by letting clients specify the response structure. REST remains simpler for straightforward CRUD operations and benefits from better HTTP caching support.

The N+1 query problem is a common performance pitfall in GraphQL. When a query requests a list of items and a related field on each, a naive resolver fetches the parent list (1 query) then fetches related data for each item individually (N queries). The DataLoader pattern solves this by batching and deduplicating database queries within a single request, collecting all needed keys and making one batched fetch instead of N individual ones.

GraphQL excels for complex, interrelated data that different clients consume differently, and is particularly valuable for mobile applications where minimizing payload size matters. For simple CRUD APIs with one or two clients, REST is often simpler and more appropriate. For internal microservice communication, gRPC is typically a better fit. Authentication in GraphQL is handled outside the query layer, usually via HTTP headers (Bearer tokens, session cookies) processed by middleware before resolvers execute. Authorization logic is implemented in resolvers or a dedicated authorization layer, and the context object passes the authenticated user's identity to all resolvers throughout the request.