JSON → Go
Generate Go structs with json tags from a JSON sample.
Private by design. Your input never leaves this browser. Conversions run locally on your device.
What this tool handles
- Emits Go structs with JSON tags matching the original key names.
- The package line and omitempty tags can each be switched off.
- Nested objects become their own named structs.
- Pointer types are not generated. A key that was null in every record becomes interface{}; a key null in only some keeps its type and gains omitempty.
Example
JSON sample
{"id":1,"name":"Ada","active":true}Go
package main
type Root struct {
ID int `json:"id"`
Name string `json:"name"`
Active bool `json:"active"`
}When you would use it
- Unmarshalling a response you only have a sample of — The tag on each field carries the original key spelling, so encoding/json binds created_at or first-name to an exported Go field without any further mapping.
- Field names a Go reviewer will accept — Known initialisms are capitalised in full, so user_id becomes UserID, apiURL becomes APIURL and ipAddress becomes IPAddress — the spelling revive and golint ask for, rather than UserId.
- Finding out which fields are really optional — Paste an array of two or three captured responses instead of one. A key missing from some of them is the only evidence of optionality available, and it is what puts omitempty on that field.
- Pasting into a file that already exists — Switching the package clause off emits the type declarations alone, so they drop into a models file that already has its own package line and imports.
Common questions
How do I tell an absent field from a null one?
With these types you cannot: both unmarshal to the zero value, so an empty string is indistinguishable from a key the server never sent. Change that field to a pointer, or to json.RawMessage, where the difference carries meaning.
What type does a timestamp or a price get?
A date string is typed string; time.Time is never emitted, so add it along with the parsing yourself. A whole number becomes int and a fractional one float64, so a price that happens to be 10 in the sample is typed int even though the endpoint can return 10.5.
What do I get from a top-level JSON array?
Only the struct for the element, named after your root name with a 2 appended because the root name is already taken. No named slice type is declared, so write []Root2 at the call site.
How are empty or mixed values typed?
An empty array becomes []interface{} and an empty object map[string]interface{}. An array whose elements are of different types also collapses to []interface{}, since a single slice type has to cover all of them.
Related tools
- JSON → TypeScript — Generate TypeScript interfaces or types from a JSON sample.
- JSON → Zod — Generate a Zod schema from a JSON sample.
- JSON → Python — Generate Python dataclasses from a JSON sample.
- JSON → SQL — Generate a CREATE TABLE statement from flat JSON rows.
- JSON → JSON Schema — Infer a JSON Schema from a sample document.
- Convert any format — Pick an input format and an output format and convert between any pair.