JSON to Entity Class
Generate C#, Java, Go and TypeScript classes from JSON instantly
How to Use
Hand-writing entity classes from a JSON sample is tedious: many fields, deep nesting and every type needs double-checking. Let this tool do it: paste a JSON snippet, pick a target language (C#, Java, Go or TypeScript), and every field gets a mapped type - integers, decimals, strings, booleans, arrays and nested objects each map to the right language type. Integers beyond the 32-bit range are promoted to long automatically, and nested objects are extracted into separate classes named after their keys.
The generated code follows each language's conventions: C# uses public properties with get; set;, Java emits private fields with getters and setters, Go produces a struct with json tags, and TypeScript produces an interface. The class name is customizable, and the tool reports how many fields and nested classes were detected so you can verify at a glance. Everything runs locally in your browser, so sample API data never leaves your device - just copy and paste into your project.
FAQ
How are field types inferred?
From the JSON value: booleans map to bool/boolean, integers map to int (promoted to long beyond the 32-bit range), decimals map to double or float64 and strings map to string. Null fields become nullable strings, and empty arrays fall back to a list of strings or any[].
How are nested objects and arrays handled?
Nested objects are extracted into separate classes named with the PascalCase of their key. Arrays of objects use the first element as the sample and emit the language's list type, such as List<T> in C#, []T in Go or T[] in TypeScript.
Will the generated code compile as-is?
The output is ready to drop into a project. C# code using List may need using System.Collections.Generic, and Java needs java.util.List imported, so a quick pass to match your project's naming conventions is recommended.