Why use this web tool instead of graphql-codegen?

While CLI codegen tools are powerful for large automated repositories, they require extensive configuration and dependencies. This browser utility generates clean types in one click for quick integration and prototyping.

How are custom scalars handled?

Custom scalars (such as DateTime, JSON, or UUID) are mapped to sensible defaults (string or any/unknown) and can be adapted to specific types like Date in your project.

Should I generate interfaces or type aliases?

Use interfaces if you plan to extend or augment definitions across declaration files. Use type aliases if you prefer union types and functional composability.

Does this support GraphQL input types?

Yes, both response types ('type') and argument payloads ('input') are fully parsed and converted into proper TypeScript contracts.

Are my GraphQL queries sent to a remote server?

No. All parsing and TypeScript code generation runs entirely within your browser runtime with 100% privacy and zero external network transmission.

GraphQL to TypeScript Type Converter

HOT

Instantly compile GraphQL SDL schemas, inputs, queries, and enums into clean TypeScript interfaces and types.

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Interactive Client Mode

Syntax:

Nullable:

GraphQL SDL Schema

Generated TypeScript DefinitionsReady for types.ts

export enum UserRole {
  ADMIN = "ADMIN",
  EDITOR = "EDITOR",
  VIEWER = "VIEWER",
}

export interface User {
  id: string;
  username: string;
  email: string | null;
  role: UserRole;
  posts: Post[];
}

export interface Post {
  id: string;
  title: string;
  content: string;
  viewCount: number;
  isPublished: boolean;
  publishedAt: string | null;
}

export interface CreateUserInput {
  username: string;
  email: string | null;
  role: UserRole | null;
}

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GraphQL SDL & Query to TypeScript Interface Compiler

GraphQL provides an expressive query language that allows clients to declare exactly the data shapes they require. However, when consuming GraphQL APIs in modern TypeScript frontends (React, Next.js, Vue), manually maintaining corresponding TypeScript types for every SDL type, enum, and query response is exceptionally tedious and prone to synchronization regressions.

By instantly compiling GraphQL Schema Definition Language (SDL) constructs—including type, interface, union, enum, and input definitions—into clean TypeScript interfaces and type aliases, engineering teams achieve true end-to-end type safety across the network boundary.

OrvoKit GraphQL to TypeScript Compiler accurately maps core scalars (Int, Float, String, Boolean, ID), custom scalars, nullable fields, optional attributes, and nested list structures into idiomatic TypeScript definitions without requiring heavy command-line codegen pipelines.

GraphQL Lexical Parsing & TypeScript AST Mapping

The architectural compiler mechanism that translates GraphQL AST nodes into idiomatic TypeScript declarations.

SDL to TypeScript Mapping FunctionMathematical Formulation

MapType(GQL) = GQL.NonNull ? Resolve(GQL.Inner) : Resolve(GQL.Inner) | null | undefined

Fields lacking an exclamation mark (!) in GraphQL are inherently nullable. They are compiled into 'Type | null' or optional fields 'key?: Type', while bracketed lists [Type] map to standard array signatures Type[].

Compiling a User SDL Block to TypeScript

Parse Input SDLtype User { id: ID!, name: String!, email: String, roles: [Role!]! }Extracted 4 field definitions

Compile Non-Null Primitivesid: string; name: string;Mapped to standard primitive types

Handle Nullable Fieldemail?: string | null;Mapped to optional nullable string

Emit Final Interfaceroles: Role[]; export interface User { ... }Complete typed interface emitted

👉 Provides immediate type safety across client network requests and component prop boundaries.

GraphQL Built-in Scalars to TypeScript Mapping Reference

Standardized type translation specifications between GraphQL SDL and TypeScript syntax

GraphQL SDL Syntax	Nullability	TypeScript Mapping	Semantic Context	Usage Example
ID!	Non-Null	string \| number	Unique resource identifier	id: string
String!	Non-Null	string	UTF-8 character sequence	username: string
String	Nullable	string \| null (or string?)	Optional text field that may return null	bio?: string \| null
Int! / Float!	Non-Null	number	32-bit signed integers and double floats	count: number
Boolean!	Non-Null	boolean	True/False boolean flag	isActive: boolean
[String!]!	Non-Null List & Item	string[]	Required array containing non-null strings	tags: string[]
[String]	Nullable List & Item	(string \| null)[] \| null	Array and inner elements may both be null	notes?: (string \| null)[] \| null
enum Role { ADMIN, USER }	Enum Declaration	export enum Role { ADMIN = 'ADMIN', USER = 'USER' }	TypeScript enum or union equivalent	Union: 'ADMIN' \| 'USER'

* Always observe GraphQL exclamation marks (!) to ensure accurate nullable typing in TypeScript.

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How to Use

11. Input GraphQL SDL or Query

Paste your GraphQL SDL snippet or query into the editor, or click [Load Sample] to inspect a structured e-commerce schema.

22. Select TypeScript Generation Mode

Choose between interface or type alias declarations, optional field syntax (? vs | null), and custom scalar mappings.

33. Copy Compiled TypeScript

Inspect the real-time generated TypeScript code and click [Copy] to transfer the definitions directly into your types.ts file.

44. Integrate into Your Codebase

Use the generated types inside Apollo Client, Urql, TanStack Query, or Next.js Server Components with complete autocomplete.

Practical Full-Stack Applications

Common scenarios where fast web-based schema compilation streamlines workflow

React Apollo Client Query Typing

Strictly type useQuery return payloads and mutation input variables without CLI bloat.

Next.js Server Component Fetching

Ensure GraphQL responses consumed in App Router server components are fully typed.

Backend GraphQL Resolver Implementation

Quickly create TypeScript interfaces for Resolver parent models and argument objects.

Lightweight SDK Packaging

Produce clean declaration files (.d.ts) for distributed third-party client libraries.

💡 Professional GraphQL TypeScript Techniques

✓ Standardize ID as String

Even if your database uses numeric primary keys, GraphQL IDs are serialized as strings. Type them as string to avoid typecasting friction.

✓ Prefer Union Types for Enums

If tree-shaking and runtime bundle size are priorities, compile enums to string unions rather than native TypeScript enums.

✓ Keep Inputs Explicitly Suffix-Named

Preserve the Input suffix on input argument interfaces (e.g., UpdateProfileInput) to clearly delineate them from entity types.

⚠️ Common Pitfalls & Mistakes to Avoid

❌ Assuming Non-Null by Default

✅ Unlike TypeScript where properties are required unless marked with ?, GraphQL fields are nullable by default unless marked with !. Never omit null checks for unmarked fields.

❌ Overlooking Array Nullability Tiers

✅ Differentiate between nullable arrays [Item]! vs arrays of nullables [Item!] vs completely nullable lists [Item].

Frequently Asked Questions (FAQ)

Expert answers to the most frequently asked questions and edge cases.

6 Q&As

Schema Definition Language (SDL) is the universal, human-readable specification syntax used to describe the schema of a GraphQL API independently of any programming language.

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