JSON to Go Structs - Generate Go Types from JSON Free

Use the free JSON to Go Structs below: your data never leaves your browser — all work happens on your device, and nothing is uploaded to any server.

Turn JSON Into Go Structs With Tags in Seconds

Go developers meet this chore constantly: an API returns JSON, and you need structs to decode it. Writing those structs by hand means translating every field name, deciding every type, and adding a json tag to each field so Go’s exported names map back to the original keys. It is mechanical work, and mechanical work is exactly what a tool should do. This free JSON to Go converter generates those structs instantly, with correct tags, from any JSON you paste, entirely in your browser.

The output follows Go conventions. Field names are exported, capitalised, and converted from any key style: “zip” becomes Zip, “user_name” becomes UserName, and “first-name” becomes FirstName. Each field carries a json tag with the original key, like `json:”user_name”`, so encoding and decoding round-trip exactly. Nested objects become their own structs, arrays become slices, and numbers without decimals become int while numbers with decimals become float64, matching how Go’s encoding/json package actually decodes them.

Why Structs Beat Maps in Go

Go lets you decode JSON into a map[string]interface{}, and for a quick script that is fine. For anything larger, it is a trap. Every field access becomes a type assertion, every typo becomes a runtime panic or a silent zero value, and the shape of your data lives nowhere in the code for the next developer to read. A struct fixes all of that. Field access is checked at compile time, a missing field is a clear error rather than a mystery, and the struct itself documents the API response.

Structs also make your code faster and smaller. Decoding into a struct avoids the allocation overhead of nested maps and interface values, and the resulting values are plain Go values you can pass around, test, and print without ceremony. When the API changes, you update the struct and the compiler shows you every affected use. That is the Go way: explicit types, checked early, with no surprises at runtime.

How to Use the Output

Paste your JSON, press Convert to Go, and copy the result into a .go file. The root struct is named Root by default, so rename it to something meaningful for your project, like ApiUser or ProductResponse. If your JSON has nested objects, each one gets its own struct, named after its field, so an address object becomes an Address struct. Arrays of objects become slices of the singular-named struct, so a “tags” array of objects becomes []Tag.

Then decode with the standard library: create a variable of your struct type, call json.Unmarshal on the response bytes, and check the error. That error check matters. Go’s decoder is forgiving: it ignores unknown fields and leaves missing fields at their zero values, so a successful decode does not guarantee complete data. If a field must be present, validate it after decoding rather than assuming the API always sends it.

Types, Tags, and Honest Limits

The type mapping follows Go’s decoding rules closely. JSON strings become string, booleans become bool, integers become int, and floating point numbers become float64. Null becomes interface{}, because Go has no null type and an empty interface is the honest representation of “anything or nothing”. Empty arrays become []interface{} for the same reason: with no example item, inventing a type would be guessing, and Go programmers rightly distrust guesses in generated code.

One limit to know: the tool infers array types from the first item. If your array mixes types in production, or if a field is sometimes a string and sometimes a number, the generated struct will reflect only the sample you pasted. For those fields, replace the generated type with interface{} or a custom UnmarshalJSON method. The tool does the mechanical 90 percent; the genuinely ambiguous cases deserve your judgement, and they are rare enough that hand-fixing them is cheap.

Where This Fits Your Workflow

Backend developers use this tool when integrating a third-party API, when scaffolding a new service around an existing JSON schema, and when writing tests, because a typed struct makes test fixtures self-documenting. It is also useful in reverse: paste a sample of what your own API returns, generate the struct, and compare it with the struct your code actually uses. Differences between the two reveal drift between your implementation and your documentation, which is worth knowing before your users find it.

Privacy is a real advantage here. API samples often contain real user data, internal IDs, or staging credentials, and pasting those into a server-side converter means trusting a stranger’s server. This tool runs entirely in your browser, so your JSON never leaves your device. Paste, convert, copy, close the tab, and nothing of yours remains anywhere else.

Frequently Asked Questions

Why do field names change? Go requires exported fields to start with a capital letter. The json tag preserves the original key, so decoding still matches the JSON exactly.

What about keys with spaces or special characters? They are converted to valid Go identifiers by splitting on non-alphanumeric characters and capitalising each part. The original key stays in the tag.

Does it handle deeply nested JSON? Yes. Each level becomes its own struct, and the output lists them in dependency order.

Paste your JSON, grab your structs, and get back to writing Go.

JSON to Go Structs – Generate Go Types from JSON Free