JSON to TypeScript

Infer types from every sample value.

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JSON to TypeScript processes your input in this browser. Inputs and results are excluded from analytics. Recent tools save tool names, visit counts and last-visit times. Saved tools store only their names. Draft saving is optional and stays on this device; delete saved text with the draft controls. Loading text from a URL is optional and contacts that server; its URL and your IP address are visible to the server. An optional “Use in” action keeps a handoff in this tab. The next tool removes it on arrival and ignores it if more than a minute has passed.

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Updated 2026-09-20

JSON to TypeScript explained

Infer a TypeScript type from a JSON sample. Every array element contributes to the type union, object keys are quoted safely, null remains null and an empty array becomes unknown[] rather than an invented element type.

Next: TypeScript formatter

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Next: JSON Lines explorer

A worked example

A sample {"a":1} produces a type with "a": number. A mixed array [1,"x"] produces Array<number | string>.

Before you use the result

A sample cannot prove every future shape. No missing property is guessed or made optional. Review the inferred type against your actual API contract.

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ToolOctopus. “JSON to TypeScript.” Updated 2026-09-20. https://tooloctopus.com/json-to-typescript.

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