JSON to multi-language entities

Processed locally

app.codegen.view

You can also load data via #data={"name":"Ada"} or #url=... It is cleared from the address bar after it is read.

Paste a sample JSON document, infer the nested structure, and generate types or entity classes for TypeScript, Go, Java, and more. Fits a “API first, models later” flow. Switch languages in the workbench dropdown; the same data is regenerated.

Type inference

Guesses string / number / boolean / array / object from values. Nested objects become separate types, reducing any.

Empty arrays, null, and mixed shapes in the same array need a human check.

Nested types are split out

Deep objects usually become separate types instead of collapsing to any. Treat the output as scaffolding, then rename to match team conventions.

Twenty languages cover common backends and clients, so you do not need a different site for each language.

Still review by hand

Confirm null and mixed-type arrays in the output. Dates, money, and enums cannot be known precisely from one example.

Generated code is not sent to a server.

Example

Sample JSON

{
  "id": 1,
  "title": "hello",
  "tags": ["json", "tools"]
}

Possible TypeScript output

interface Root {
  id: number
  title: string
  tags: string[]
}

Which languages are supported?

TypeScript, Java, Go, Python, C#, Rust, Kotlin, Swift, and 20 in total. Switch them in the workbench.

Is generated code sent to a server?

No. Inference and template expansion run in the browser.

Is this production-ready?

Treat it as a draft. You still add validation, serialization annotations, optional fields, and team naming.

What if a field name is not a legal identifier?

Names are converted to identifiers the target language can use. Rename keyword collisions by hand.

Recommended workflow

Prepare a complete sample JSON (including nesting and arrays).
Start with TypeScript, then switch to the language you actually use.
Copy into the project and fill in nulls, dates, and enums.
After the API changes, Diff the samples and regenerate the conflicting layer.

The generator does not know “this number is money.” People still add product meaning. Do not treat the draft as a contract.