JSON to Go Struct Converter

Turn a JSON sample into Go struct definitions with json tags, ready for encoding/json. Keys become exported Go names with the standard initialisms (id → ID, avatar_url → AvatarURL), numbers become int or float64 depending on the values seen, sometimes-null fields become pointers, and fields missing from some array items get omitempty. The output uses aligned fields; run gofmt after pasting it.

How to use this tool

1. Paste a representative JSON sample; arrays with several items give the best types.
2. Set the name of the top-level struct.
3. Choose separate named types or inline anonymous structs for nested objects.
4. Copy the code into your package and adjust any names or types you want to change.

Formula

string → string · whole numbers → int (int64 if beyond 32 bits) · decimals → float64 · true/false → bool · [ … ] → []T · { … } → struct · null or mixed → any

Values found at the same place are merged across array items. If a number is a decimal in any item, the field becomes float64. A field that is null in some items becomes a pointer (*string); one that is null in every item, or holds different kinds of value, becomes any. Each field gets a tag such as json:"avatar_url" so encoding/json maps it back to the original key. Duplicate keys and numbers outside the supported finite, safe-integer range are rejected; other decimals use JavaScript precision.

Example

The sample record gives three types. Root has ID int, Name string, Email string, Active bool, Score float64, Tags []string, Address Address, Orders []Order and Manager any. Address has three string fields. Order has ID string, Total float64 (25.5 and 12 are merged to float64), Items int and Coupon string with json:"coupon,omitempty", because only one order has a coupon.