Paste JSON and auto-generate TypeScript interfaces with nested type inference and optional properties.
JSON to TypeScript Interface Generator reads a valid JSON sample and drafts TypeScript interface declarations for the object shapes it contains. Property names and observed values guide the inferred property types, while nested objects produce nested type definitions and supported shape differences can produce optional properties. The important limitation is that the result describes evidence in the pasted sample, not every value an API might return. Treat the generated interfaces as an editable starting point rather than a verified contract or runtime validator.
The generator examines the JSON value's structure. Object members become TypeScript properties, and strings, numbers, booleans, arrays, objects, and null values provide evidence for their corresponding property types. Nested object shapes are represented through additional interface declarations so that the result remains reusable and readable instead of expanding every nested object inline.
Where the observed JSON structures do not consistently establish that a member is present, the generator can express that member with TypeScript's optional property marker, such as `nickname?: string`. This is a type-level description of possible absence. It does not add a default value, test incoming data, or prove that the source system officially treats the field as optional.
No. TypeScript interfaces describe values during type checking and are not runtime validators. The generator can help type code that consumes the sample's shape, but an external response can still violate that shape. Use runtime parsing or validation when data crosses a trust boundary, then assign the validated result to the generated or revised interface.
It can generate optional properties when the supplied structures provide evidence for them. No sample-based generator can establish all presence rules from examples alone. Explicit null and an absent member are also different cases. Compare every generated `?` marker with the API specification, representative payloads, or application requirements before relying on it.
The behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
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