Free online JSON to TypeScript interface tool, auto-generate interface and type, supports nested objects and arrays
TL;DR: Free JSON to TypeScript interface tool. Auto-generate interface and type with smart type inference, supports nested objects and arrays.
This tool runs entirely in your browser. Open DevTools → Network panel and search your input — it appears in no request.
FAQ
Completely free, no registration or login required. Convert JSON to TypeScript interfaces directly in your browser — all parsing runs locally with no usage limits.
Yes. It correctly recognizes nested objects, arrays, and element types within arrays, automatically inferring interfaces while preserving the hierarchy.
No. All conversion runs locally in your browser. Your data is never sent to any server, ensuring complete privacy.
Related Tools
Related Articles
JSON to TypeScript: Complete Guide to Auto-Generating Type Definitions
Step-by-step tutorial on how to quickly convert JSON data to TypeScript interfaces and type definitions, boosting development efficiency and code quality
Unexpected token '<' is not valid JSON — 5 Reasons Your API Returned HTML Instead
fetch throws SyntaxError: Unexpected token '<' when the response body is HTML, not JSON. Covers the 5 root causes: SPA history fallback returning index.html, auth 302 redirects, gateway 502 error pages, wrong baseURL, and missing res.ok checks — with curl diagnostics.
JSON Troubleshooting Handbook: From Error Message to Fix (Symptom Index)
JSON errors that make no sense? This handbook organizes fixes by symptom — syntax errors, Unicode escaping, encoding mojibake, and Schema validation failures, with a diagnostic tree and a general debugging workflow.