json to go struct converter
typetools
instant, client-side type converter • 0ms network latency
package models
type Metadata struct {
LastLogin string `json:"lastLogin"`
IpAddress string `json:"ipAddress"`
FailedAttempts any `json:"failedAttempts,omitempty"`
}
type RootPayload struct {
UserId string `json:"userId"`
Username string `json:"username"`
Email string `json:"email"`
IsActive bool `json:"isActive"`
Score float64 `json:"score"`
Roles []string `json:"roles"`
Metadata Metadata `json:"metadata"`
Tags []any `json:"tags"`
}step-by-step integration guide
technical specification differences & end-to-end conversion workflow
Bridging Dynamic JSON Payloads and Go's Static Memory Layout
Go (Golang) compiles structs into contiguous memory blocks with fixed field offsets known at compile time, whereas JSON is a dynamically typed, schema-less text serialization format. When unmarshaling JSON via Go's standard library encoding/json package, reflection is used to map incoming UTF-8 JSON keys to exported Go struct fields. In Go, a struct field is only visible to the reflection unmarshaler if its identifier begins with an uppercase ASCII letter (PascalCase). Because REST API payloads typically use snake_case or camelCase keys, every generated Go field must be paired with an explicit raw string struct tag (e.g., `json:"user_id,omitempty"`) to bind the wire format name to the exported memory symbol.
AST Type Inference, Pointer Semantics, and Slice Merging
To synthesize production-ready Go code, our converter inspects the JSON syntax tree across all sibling array elements. First, JSON numbers are inspected for fractional components: whole integers map to int64 (or int), while decimals map to float64 to avoid truncation during json.Unmarshal. Second, when the AST engine encounters nullable fields or keys that appear in only a subset of objects inside an array, it promotes the Go field type to a pointer (such as *string or *int64) and appends the ,omitempty tag option. Using pointers allows Go applications to distinguish between an explicit null/missing JSON field (nil pointer) and a zero-value primitive ("" or 0). Nested objects can be emitted either as inline anonymous structs or extracted as reusable top-level named struct definitions.
frequently asked questions
common developer questions answered
q:When should a Go struct field use a pointer (*string) instead of a value (string) for JSON?
In Go, value types always initialize to their zero value ("" for strings, 0 for ints). If your API needs to distinguish between a field being explicitly null/omitted versus being an empty string or zero, using a pointer type (*string) with omitempty is required.
q:How does the converter handle heterogeneous JSON arrays in Go?
If a JSON array contains mixed primitive types (such as strings and numbers in the same array), Go's static type system cannot use a single primitive slice, so the generator emits []any (or []interface{}) to prevent unmarshaling panics.
q:Does the generator automatically parse ISO-8601 date strings as time.Time?
Yes. When string literals match strict RFC 3339 / ISO-8601 timestamp patterns, the AST engine infers Go's standard time.Time type, which implements the json.Unmarshaler interface natively.