Convert JSON to Ruby online, free. JSON is the dominant data-interchange format for web APIs and config. Ruby keyword-init Structs give lightweight, typed-by-convention value objects. JSON to Ruby conversion parses your JSON against the ECMA-404 / RFC 8259 grammar (https://www.rfc-editor.org/rfc/rfc8259), builds an in-memory model of its keys, nested objects and arrays, then emits ready-to-use Ruby types following the Ruby Struct conventions. Processing runs in your browser in JavaScript with no upload or server round-trip — no size limit beyond your device's memory, so multi-megabyte documents convert in milliseconds and sensitive payloads never leave your machine. Typical uses include Rails & Sinatra apps, API response objects and config and DTOs.
It maps the full structure of your JSON onto idiomatic Ruby types, following the Ruby Struct conventions. 100% free, no registration, and complete privacy — everything runs locally in your browser, so your data never touches a server.
Paste JSON and generate Ruby types from Ruby immediately. Conversion runs client-side, so there is no upload wait and large documents stay fast.
Nested JSON objects, tables and arrays are mapped faithfully onto Ruby, including nested types and optional fields.
Your JSON never leaves your device — everything is processed locally in JavaScript, with nothing logged or stored.
Unlimited conversions with no account, no quotas, and no watermark. Works on desktop and mobile.
A JSON document and its Ruby equivalent:
JSON input:
{
"title": "Dune",
"pages": 412,
"available": true
}Output:
Book = Struct.new(:title, :pages, :available, keyword_init: true)Paste your JSON into the editor and press "Convert to Ruby". The tool parses it against the ECMA-404 / RFC 8259 grammar, then generates Ruby types following Ruby Struct conventions — instantly and entirely in your browser. You can validate or format the JSON first to be sure it is clean.
JSON already uses objects, arrays and typed scalars, so mapping to Ruby is close to one-to-one: objects become types or structs, arrays become lists, and numbers, booleans and null keep their types.
Optional or nullable members in the generated Ruby are inferred from keys missing in some records of your JSON, following Ruby Struct. Include the optional fields in your sample so they are typed correctly.
JSON (JavaScript Object Notation) (JSON) — JSON is the dominant data-interchange format for web APIs and config. Ruby structs (Ruby) — Ruby keyword-init Structs give lightweight, typed-by-convention value objects. This converter maps the structure of your JSON onto Ruby so you can use it for Rails & Sinatra apps.
Yes. Invalid JSON is flagged with a clear error before anything is converted. Common JSON problems to check are matched braces and brackets, double-quoted keys, and no trailing commas. Starting from clean input keeps the generated Ruby accurate.
Yes. The entire JSON-to-Ruby conversion runs locally in your browser in JavaScript — your JSON is never uploaded, logged or stored. That matters when the data is something like REST/GraphQL API payloads, which should not leave your machine.
The generated Ruby is ready for Rails & Sinatra apps, API response objects and config and DTOs. Copy or download it and drop it straight into your codebase.
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