Result

Overview

Turn sample JSON payloads into a quick TypeScript starting point. Perfect for wiring new API clients or sharing data contracts with teammates.

How to Use

Paste valid JSON
Provide a representative sample object. Arrays will derive their element type from the first item.
Set an interface name
Adjust the interface name to match your domain model. Optional fields are always included in the result.
Refine manually
Use the generated interface as a baseline and refine complex unions or nested shapes by hand.

Use Cases

Documenting APIs

Paste API responses to generate TypeScript definitions for SDKs or internal documentation.

Rapid prototyping

Infer types while experimenting in a playground without manually writing interfaces from scratch.

Onboarding teammates

Share generated interfaces to explain object structures when ramping up new developers.

Frequently Asked Questions

Does the tool detect optional properties?

Optionality is not inferred automatically. Every observed property is required so you can decide manually which ones should be optional.

How are arrays handled?

The first element determines the inferred type. Empty arrays default to `unknown[]` so you can refine them afterwards.

Concept Notes

Inferring types from imperfect samples

Type inference mirrors the data you provide: keys absent in some objects become optional, and mixed-type arrays widen to unions. Clean, representative samples yield cleaner interfaces; otherwise, post-editing the generated types or normalising data first prevents accidental any usage and keeps downstream API contracts tight.

JSON → TypeScript