JSON input
valid
TypeScript output
MariusAlch/json-to-ts on npm is a Node library and CLI for programmatic JSON-to-TypeScript conversion. This tool is a hosted browser UI for one-off pastes. Different shapes of the same need; here's when to pick which.
The npm package json-to-ts (MariusAlch) is the canonical scriptable JSON-to-TypeScript converter. You install it (`npm i json-to-ts`), import it, and call `JsonToTS(value)` to get back an array of interface declarations as strings. The CLI form lets you pipe data in from another tool. This is the right shape of the tool for build-time type generation, fixture-to-types pipelines, or generating a typed client from a recorded API response in a CI job.
This site is the same conversion algorithm exposed as a hosted browser UI. There's no install, no Node, no shell — paste JSON into the left pane and the right pane updates with TypeScript (interface or type alias), a Zod schema, or a Valibot schema. The trade-off is that you can't pipe through it: every conversion is a manual paste. For one-off type generation while you're reading API docs or debugging a webhook, that's the lower-friction path; for batch automation, it's the wrong shape.
Honest tradeoffs: pick the npm CLI/library when you want to bake conversion into a build script, run it across a directory of JSON fixtures, or chain it with other tools (jq, curl, file watchers). Pick this hosted UI when the input is a one-off JSON payload, when you don't have Node handy, or when you want Zod / Valibot output (the npm CLI is TypeScript-only). Both share the same author-of-the-algorithm DNA — they're complementary, not competitive, and many users will use both for different jobs.