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🔄 JSON → TypeScript Types
Paste any JSON example — we infer TypeScript interfaces with correct types for strings, numbers, booleans, nested objects, and arrays. Handles optional properties (null in input → optional in TS).
Examples
{ "id": 1, "name": "Alice", "active": true }interface Root { id: number; name: string; active: boolean; }{ "user": {"id":1,"tags":["a","b"]} }interface User { id: number; tags: string[]; }
interface Root { user: User; }Frequently asked questions
Are the inferred types correct?
For one example yes. But if your real data sometimes has null or missing fields, the inferred types may be too narrow. Always inspect and adjust.
Why are some types unknown[]?
When an array is empty in the sample, we can't infer the element type. Fill in by hand or provide a non-empty example.
Comparable to quicktype?
quicktype handles more languages and more sophisticated inference (unions, dates). This tool is simpler and faster for quick TS scaffolding.
About this tool
JSON → TypeScript Types runs entirely in your browser using standard Web APIs. No data is sent to any server. The source for this tool is in our public GitHub repository.
Related tools
- 📐 JSON Formatter — Format, validate, and minify JSON with syntax error highlighting.
- 🔄 YAML ↔ JSON Converter — Convert between YAML and JSON. Auto-detects direction.
- 🎲 Mock Data Generator — Generate fake names, emails, addresses, phone numbers as JSON or CSV.
Why this tool
vs typical free web-tool sites
| 1vw | Typical free site | |
|---|---|---|
| Price | Free | Free |
| Signup required | No | Often (for premium features) |
| Ads inside the tool | No | Yes (banner + video) |
| Data sent to server | No (browser-only) | Yes (inputs analyzed for ads) |
| Total tools | 96 | Often <20 or scattered across sites |
| Bookmarkable URL per tool | Yes | Mixed |
| Loads in under 1s | Yes (static) | Often slow (ad tracking) |
| Multilingual | EN / ES / PT / FR / DE | Usually EN only |
| Open source | Yes | No |