Free YAML to Ruby Converter — generate keyword-init Ruby structs from YAML in your browser

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🧬 YAML to Ruby — Free Online Tool

Convert YAML to Ruby online, free. YAML is an indentation-based superset of JSON favoured for human-edited config. Ruby keyword-init Structs give lightweight, typed-by-convention value objects. YAML to Ruby conversion parses your YAML against the YAML 1.2.2 grammar (https://yaml.org/spec/1.2.2/), 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.

🚀 Why use this YAML to Ruby tool?

It maps the full structure of your YAML 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.

Key Features

Instant, in-browser

Paste YAML and generate Ruby types from Ruby immediately. Conversion runs client-side, so there is no upload wait and large documents stay fast.

🧩Structure-aware mapping

Nested YAML objects, tables and arrays are mapped faithfully onto Ruby, including nested types and optional fields.

🔒100% private

Your YAML never leaves your device — everything is processed locally in JavaScript, with nothing logged or stored.

🆓Free, no signup

Unlimited conversions with no account, no quotas, and no watermark. Works on desktop and mobile.

Popular Use Cases

Typed models from samples

  • Turn a sample YAML payload into Ruby types
  • Skip hand-writing boilerplate models
  • Keep front-end and back-end shapes in sync

Rails & Sinatra apps

  • Rails & Sinatra apps
  • API response objects
  • config and DTOs

Onboarding a new API

  • Paste an example YAML response
  • Get typed Ruby to consume it safely
  • Catch shape mismatches at compile time

What It Handles

Structure

  • Nested objects & tables
  • Arrays / lists
  • Deeply nested documents

Values

  • Inferred types (string, number, boolean)
  • Optional / nullable fields
  • Nested type names

Workflow

  • Copy or download output
  • Load an example to try it
  • Validate & format the input

Worked example

A YAML document and its Ruby equivalent:

YAML input:

label: web
replicas: 3
exposed: false

Output:

Service = Struct.new(:label, :replicas, :exposed, keyword_init: true)

Sources & References

Frequently Asked Questions

How do I convert YAML to Ruby?

Paste your YAML into the editor and press "Convert to Ruby". The tool parses it against the YAML 1.2.2 grammar, then generates Ruby types following Ruby Struct conventions — instantly and entirely in your browser. You can validate or format the YAML first to be sure it is clean.

How is YAML structure represented in Ruby?

YAML anchors and aliases are expanded and comments are dropped before Ruby is produced, and indentation defines the structure. Note that YAML 1.1 treats words like "yes" and "no" as booleans, so quote them if you want strings.

Are optional fields detected when generating Ruby?

Optional or nullable members in the generated Ruby are inferred from keys missing in some records of your YAML, following Ruby Struct. Include the optional fields in your sample so they are typed correctly.

What is the difference between YAML and Ruby?

YAML (YAML Ain't Markup Language) (YAML) — YAML is an indentation-based superset of JSON favoured for human-edited config. Ruby structs (Ruby) — Ruby keyword-init Structs give lightweight, typed-by-convention value objects. This converter maps the structure of your YAML onto Ruby so you can use it for Rails & Sinatra apps.

Does the converter validate my YAML first?

Yes. Invalid YAML is flagged with a clear error before anything is converted. Common YAML problems to check are spaces (never tabs) for indentation, consistent indent levels, and no duplicate keys. Starting from clean input keeps the generated Ruby accurate.

Is my YAML data private?

Yes. The entire YAML-to-Ruby conversion runs locally in your browser in JavaScript — your YAML is never uploaded, logged or stored. That matters when the data is something like Kubernetes & Docker Compose manifests, which should not leave your machine.

Where can I use the Ruby output?

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.

🎓 Pro Tips

  • Tip 1: Validate or format your YAML first (the Validate / Format buttons) so the converter works from clean, YAML 1.2.2-conformant input.
  • Tip 2: Give the tool a representative YAML sample — optional fields are only detected from the keys actually present, so include them if they matter.
  • Tip 3: Authoritative reference for the input format: YAML 1.2.2 — https://yaml.org/spec/1.2.2/.
  • Tip 4: For the output, follow the Ruby Struct (https://docs.ruby-lang.org/en/master/Struct.html) conventions in your codebase.