module YAML

YAML Ain’t Markup Language

This module provides a Ruby interface for data serialization in YAML format.

The YAML module is an alias of Psych, the YAML engine for Ruby.


Working with YAML can be very simple, for example:

require 'yaml'
# Parse a YAML string
YAML.load("--- foo") #=> "foo"

# Emit some YAML
YAML.dump("foo")     # => "--- foo\n...\n"
{ :a => 'b'}.to_yaml  # => "---\n:a: b\n"

As the implementation is provided by the Psych library, detailed documentation can be found in that library’s docs (also part of standard library).


Do not use YAML to load untrusted data. Doing so is unsafe and could allow malicious input to execute arbitrary code inside your application. Please see doc/security.rdoc for more information.


Syck was the original YAML implementation in Ruby’s standard library developed by why the lucky stiff.

You can still use Syck, if you prefer, for parsing and emitting YAML, but you must install the ‘syck’ gem now in order to use it.

In older Ruby versions, ie. <= 1.9, Syck is still provided, however it was completely removed with the release of Ruby 2.0.0.

More info

For more advanced details on the implementation see Psych, and also check out for spec details and other helpful information.

Psych is maintained by Aaron Patterson on github:

Syck can also be found on github: