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Convert JSON objects to TypeScript interfaces instantly with customizable options and clean code generation
Transform JSON data into clean, well-typed TypeScript interfaces instantly. Our free online converter helps developers, API designers, and TypeScript enthusiasts generate accurate type definitions with support for nested objects, arrays, and customizable options. Perfect for API integration, data modeling, and maintaining type safety in TypeScript projects.
Real-time TypeScript interface generation
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Accurate type inference from JSON data
Converting JSON to TypeScript interfaces is the process of analyzing JSON data structure and generating corresponding TypeScript type definitions. This process ensures type safety, better IDE support, and improved code maintainability in TypeScript projects.
Our tool automatically detects data types from JSON values, handles nested objects and arrays, and generates clean, readable TypeScript interfaces that you can immediately use in your projects. With customizable options for optional properties, readonly modifiers, and naming conventions, you get exactly the interfaces you need.
The tool parses your JSON input and analyzes the structure, identifying data types, nested objects, and array patterns to understand the complete data schema.
Each JSON value is mapped to its corresponding TypeScript type: strings to string, numbers to number, booleans to boolean, arrays to typed arrays, and objects to interfaces.
The tool generates clean TypeScript interfaces with proper naming conventions, handling nested structures and creating separate interfaces for complex objects.
Apply your preferred options like optional properties, readonly modifiers, export statements, and naming conventions to match your coding standards.
Catch type errors at compile time instead of runtime, preventing bugs and improving code reliability.
Get autocomplete, IntelliSense, and refactoring tools that understand your data structure.
Interfaces serve as living documentation for your data structures and API contracts.
Shared type definitions ensure consistent data handling across team members and projects.
Convert API response examples to TypeScript interfaces for type-safe API client development and better integration with REST APIs, GraphQL, and microservices.
Model complex data structures from JSON samples, creating consistent type definitions for databases, data processing pipelines, and state management.
Convert existing JavaScript projects to TypeScript by generating interfaces from configuration files, API responses, and data structures.
Create type-safe mock data and test fixtures by converting sample JSON data to TypeScript interfaces for unit tests and integration tests.
To convert JSON to a TypeScript interface, paste a JSON object or array into the input editor and set the Root Interface Name; the output regenerates as you type. Copy the output or download it as a .ts file named after the root interface. The input also accepts JavaScript object syntax with unquoted keys, single quotes and trailing commas.
This JSON to TypeScript converter generates interface declarations for objects, with an optional export keyword. A type alias is used only when the root is not an object, such as a top-level array (type Root = RootItem[]) or a single string or number. For plain object shapes the two are interchangeable, so you can change interface User { to type User = { if your codebase prefers aliases.
A property is marked optional (?) when it is missing from some of the objects that share an interface, such as items in the same array. A null value is typed as null, or added to a union like string | null when other samples hold a string; a field that is null everywhere stays null, so widen it by hand. The Make properties optional setting adds ? to every property, and Make properties readonly adds readonly to every property.
Each nested object becomes its own interface named after its key in PascalCase, so address becomes Address. Arrays of objects get one interface named from the singular key (users becomes User[]), built by merging every element, so keys missing from some elements become optional and differing value types become unions. Mixed arrays of primitives become union arrays such as (string | number)[], and empty arrays become any[].
Paste the array as it is: a top-level JSON array becomes an item interface plus a type alias for the array, such as export type RootInterface = RootInterfaceItem[]. The item interface merges every element, so a key that only some elements have is marked optional. An array of primitives becomes a single alias such as type RootInterface = number[].
JSON to TypeScript infers types from a sample of real data, so it only knows the fields and values present in that sample. JSON Schema to TypeScript tools such as json-schema-to-typescript read a schema that declares required fields, enums and unions, so their output reflects the full contract. Use a sample converter for quick API typing and a schema-based generator when a schema exists.
Start generating TypeScript interfaces from your JSON data today and improve your development workflow.
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