JSON in Ruby — Parse, Generate & Work with Hashes

Ruby's standard library includes the json gem. Require 'json' to access JSON.parse() and .to_json.

Parse a JSON string

JSON.parse() returns a Hash with string keys by default.

require 'json'

json_string = '{"name":"Alice","age":30,"active":true}'
data = JSON.parse(json_string)

puts data['name']   # Alice
puts data['age']    # 30
puts data.class     # Hash

Parse with symbol keys

Pass symbolize_names: true to use symbols instead of strings as hash keys.

data = JSON.parse(json_string, symbolize_names: true)

puts data[:name]  # Alice

Generate JSON

Call .to_json on any Hash, Array, String, Integer, Float, true, false, or nil.

data = { name: 'Alice', scores: [95, 87], active: true }
puts data.to_json
# {"name":"Alice","scores":[95,87],"active":true}

# Pretty-print
puts JSON.pretty_generate(data)

Read a JSON file

Read the file contents and parse with JSON.parse().

require 'json'

data = JSON.parse(File.read('data.json'))
puts data['name']

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Frequently Asked Questions

How do I parse JSON in Ruby?▾

Require 'json' and call JSON.parse(json_string). It returns a Hash with string keys. Pass symbolize_names: true to use symbol keys instead.

How do I generate JSON in Ruby?▾

Call .to_json on any Hash, Array, String, Integer, Float, true, false, or nil. For pretty output use JSON.pretty_generate(data).

How do I read a JSON file in Ruby?▾

Use JSON.parse(File.read('file.json')). Add symbolize_names: true if you prefer symbol keys. For large files, use the json gem's streaming API.

How do I handle JSON parse errors in Ruby?▾

JSON.parse raises JSON::ParserError on invalid input. Rescue it: begin; JSON.parse(str); rescue JSON::ParserError => e; puts e.message; end.

What is the difference between JSON.parse and JSON.load in Ruby?▾

JSON.load is designed for trusted data only — it can deserialize arbitrary Ruby objects and is unsafe with user input. Always use JSON.parse for untrusted JSON strings.

JSON in Other Languages

JSON in Python →JSON in JavaScript →JSON in TypeScript →JSON in Go →JSON in Java →JSON in PHP →JSON in C# →JSON in Rust →JSON in Kotlin →JSON in Swift →JSON in Dart →JSON in Scala →JSON in Next.js →JSON in Express →JSON in FastAPI →JSON in Django →JSON in Terraform →

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