How are JSON numbers typed in Go?

A number maps to int64 when every value is a whole number, and to float64 when it has a fractional part. Mixed numeric arrays collapse to []float64 so they stay numeric.

How are nested objects and arrays handled?

Each nested object becomes its own exported struct named after the PascalCased key, referenced as a pointer, and arrays become []T. A mixed-type array falls back to []interface{}. Every field gets a json:"originalKey" tag.

Is my JSON uploaded anywhere?

No. The inference runs entirely in your browser with JavaScript — your data is never sent to a server or stored.

JSON to Go Struct — Gera Tools

Generate Go structs from JSON

Decoding JSON in Go means defining a matching struct with the right field types and json:"..." tags by hand — tedious and error-prone for nested payloads. This tool infers typed Go structs from a representative JSON sample so you can paste them straight into your project.

How it works

The generator walks the sample and maps each value to a Go type, building nested structs as it goes:

JSON	Go type
integral number	`int64`
fractional number	`float64`
mixed numeric array	`[]float64`
string	`string`
boolean	`bool`
object	its own exported struct (pointer)
array of T	`[]T`
mixed array	`[]interface{}`

Field names are PascalCased, with common initialisms like ID and URL capitalised the way Go’s style guide expects, and every field gets a json:"originalKey" tag.

Example

This JSON:

{ "id": 7, "user": { "name": "Sam" } }

generates:

type Root struct {
	ID   int64 `json:"id"`
	User *User `json:"user"`
}

type User struct {
	Name string `json:"name"`
}

Because the types are inferred from one sample, treat the output as a strong starting point. All inference happens in your browser — your JSON is never uploaded or stored.