JSON to TypeScript Converter | Interfaces & Types
Paste JSON to generate production-ready TypeScript interfaces or type aliases with smart inference for arrays and nested objects. Everything runs locally in your browser for privacy and speed—perfect for APIs, configs, and data models.
How to Use This Tool
- 1
Paste your JSON into the input
- 2
(Optional) Set a name for the root interface/type
- 3
Choose Interface or Type and run conversion (Live or Manual)
- 4
Copy the generated TypeScript into your project
- 5
(Optional) Review optional/null fields and refine as needed
Use Cases & Examples
REST API Integration & Type Safety
Generate types from API responses for autocomplete, compile-time checks, and safer refactors.
Reducing Boilerplate & Accelerating Development
Create interfaces automatically to save time and avoid hand-written typos.
Configuration & Data Structure Typing
Derive types for configs, feature flags, and fixtures to keep access type-safe across the app.
Learning TypeScript & Type System Understanding
See JSON map to TypeScript instantly to learn structural typing patterns.
Type System & Inference (Brief)
Leveraging structural typing, the tool inspects sample values to infer objects, arrays, primitives, and literal unions where possible.
It outputs interfaces or type aliases with nested declarations and sensible defaults for array element types.
Known limits: optionality is unknown from a single sample; empty arrays default to any[] unless hints are provided.
Frequently Asked Questions
Q.What's the difference between TypeScript 'interface' and 'type'? Which should I use?
A. Interfaces support declaration merging and extends; type aliases excel at unions and complex compositions—pick based on team conventions and use case.
Q.How does the tool handle nested objects and arrays?
A. The tool infers nested shapes and array element types automatically, then emits matching interfaces or type aliases.
Q.Can I specify optional properties? How are nullable values handled?
A. A single sample can’t prove optionality—generate types, then mark fields with ? or add "| null" where needed.
Q.What happens with invalid or malformed JSON?
A. Malformed JSON is rejected with clear parse errors before any type generation.
Related Tools
Explore more developer tools
JSON Formatter & Validator | Format, Minify, Validate
Format, validate, and minify JSON with instant error highlights—fully local.
JSON Validator | Validate & Debug JSON Syntax
Live JSON validation with exact line/column errors—fully local in your browser.