JSON to Code Generator

Paste any sample JSON; the generator infers a schema from the structure and emits typed code. Languages supported:

• TypeScript — interface with optional (?) fields where the sample had nulls.
• C# / .NET — class with [JsonPropertyName("...")] for System.Text.Json, PascalCase properties, nullable reference types where appropriate.
• Go — struct with json tags. omitempty added for pointer/nullable fields.
• Python — @dataclass or pydantic.BaseModel. Type hints from typing.
• Java — POJO with Jackson @JsonProperty annotations, standard getter/setter pairs.
• Kotlin — data class with @SerialName for kotlinx.serialization or Moshi.
• Swift — struct conforming to Codable.
• Rust — struct with serde derives (Serialize, Deserialize).

Nested objects become named types, arrays of objects become List<T> / [T] / Vec<T> in the target language's idiom.

quicktype.io was the dominant JSON-to-code generator for years. BuildStudio's equivalent covers the same major languages with some differences worth knowing:

• No signup, no rate limit. quicktype's hosted version has started adding limits; ours is always free and unlimited.
• In-browser only. Your JSON never hits our servers. Safe for proprietary API response samples.
• Faster round-trip. No loading state; paste → instant output.
• Fewer rare languages. quicktype also supports Objective-C, Haskell, Dart, Crystal, Ruby, Elm. If you need those specifically, use quicktype.
• Same underlying approach. Both tools infer a union schema from the sample, then emit language-idiomatic code. Output quality is comparable.

Best workflow: paste an API response here, get the DTO class, paste into your project, iterate. Faster than writing the DTO by hand from memory or OpenAPI generators.

A common task when integrating a third-party API in ASP.NET Core / .NET projects. Step-by-step:

1. Fetch a sample response — call the API with our API Tester, copy the JSON body.
2. Paste into the generator here, select C# / .NET.
3. Copy the generated class into your project. The output uses [JsonPropertyName] attributes so property names on the wire don't have to match your PascalCase C# property names.
4. Use with HttpClient + JsonSerializer: await client.GetFromJsonAsync<YourClass>(url).
5. Adjust for optional fields — the generator marks nullable where the sample had nulls, but nothing beats reading the API's own schema docs.

// Usage example
using System.Net.Http.Json;

var client = new HttpClient();
var response = await client.GetFromJsonAsync<UserResponse>("https://api.example.com/user/1");
Console.WriteLine(response.Name);