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devsmiths

JSON to C#

Generate C# classes with attributes from a JSON sample.

TypeScriptGoPythonC#RustJavaSwiftKotlin
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What this tool does

Generate C# classes with serializer attributes from a JSON sample. Use the namespace option to scope the generated types to your project. Powered by quicktype, runs entirely in your browser.

How to use it

Paste JSON (or load the example) and read the C# classes on the right. Set the namespace in the options pane to drop the file straight into your project.

Input: {"id":42,"name":"devsmiths","createdAt":"2024-03-11T08:24:00Z","stars":1280,"public":true,"contributors":[{"login":"ada","commits":51,"admin":true},{"login":"linus","commits":33,"admin":false}],"homepage":null}

Limits and edge cases

  • Single-sample inference: every field present in your sample becomes part of the type. Fields absent from the sample don’t become optional automatically — toggle all optional in the options pane if every field should be nullable.
  • The generated code is a starting point. Naming follows each language’s idiom but you’ll often want to rename types and tighten unions by hand.
  • First generation takes 1–3 seconds while the quicktype engine downloads into the Web Worker. Subsequent generations are near-instant.
  • Output for non-TypeScript targets renders without syntax highlighting in the editor pane (CodeMirror language packs for Go / Python / Rust / etc. are not bundled to keep the page light). Copy / Download still produce the correct file content.
  • The input must be valid JSON — for trailing commas, single quotes, or comments, run the JSON Repair tool first; for a quick sanity check use the Validator.
  • Background reading: JSON to TypeScript in practice walks through the workflow end-to-end, including the rename / tighten step.

Frequently asked questions

Which languages does it support?
Eight: TypeScript, Go, Python, C#, Rust, Java, Swift, and Kotlin. Switch via the segmented tabs above — the URL changes to /json/types/<language> and the output regenerates in place.
Why is the first generation slow?
The quicktype engine (~700 KB) is loaded into a Web Worker on first use. After that it's cached for the rest of the session — subsequent generations are near-instant.
Is my JSON uploaded?
No. The generator runs entirely in a Web Worker in your browser. Nothing is sent to a server.
Can I use multiple JSON samples?
Not yet — the current build infers types from a single sample, so fields absent in the sample become required-with-the-observed-type. Multi-sample inference (union types, optionality detection across samples) is on the roadmap.
Does it generate serializers?
Where the target supports it: Go gets `json:` tags, Rust gets serde derives, Java gets Jackson annotations, C# gets attributes, Swift gets Codable conformance. TypeScript emits plain interfaces. Toggle 'all optional' if every field should be nullable.
The generated code isn't perfect — can I fix it?
Yes — treat the output as a starting point. Rename types, tighten unions, mark nullables explicitly. The generator is opinionated and conservative; humans always win on naming and intent.