Generate TypeScript interfaces from any JSON — nested types named, object arrays merged — on your own device.
A .json file — or paste below · converted on your device, nothing uploaded
No size limit · files are processed on your device and never uploaded · how it works
JSON in
TypeScript out
Infers interfaces from your JSON — nested objects become named interfaces, arrays of objects are merged (keys missing in some become optional). Runs in your browser.
Runs in your browser. Files are never uploaded — you can go offline after the page loads.
Drop files, pick options, download. Whole folders at once, no signup, no daily limit.
The same engines the professionals use — SVGO, resvg, MozJPEG, libwebp, libavif — compiled to run in your browser.
Files are processed on your device and never uploaded. Close the tab and nothing remains anywhere.
Paste a JSON sample — an API response, a config, a fixture — and get TypeScript interfaces for it. Nested objects become their own named interfaces, arrays of objects are merged so a key missing from some elements is marked optional, and null values are typed so you can tighten them later.
Name the root interface, then copy the result or download a .ts file. It all runs in your browser. To tidy the JSON first, use the JSON Formatter.
When an array contains objects that don’t all share a key, that key is marked optional (?). A null value is typed as null so you can tighten it later.
Yes — each nested object becomes its own named interface (from the key name), referenced from the parent, so the output is clean and reusable.
No — inference runs entirely in your browser.
Most online converters upload your file to a server. InfyTool ships the actual encoders to your browser as WebAssembly instead, so processing happens inside your tab — faster for batches, and nothing to delete afterwards.
InfyTool is built by the same team as these free libraries.