HOWTO set a user agent for Ruby Mechanize

This guide will show you how to set a custom user agent header for Ruby Mechanize, or use one of the built-in browser aliases.

Setting a custom user agent

Use the Mechanize#user_agent= method to set a custom user agent. For example:

require 'mechanize'

mechanize =

mechanize.user_agent = 'ACME-Examplebot/1.0'

By convention the user agent header should include a list of "product tokens" (product name and version), listed in order of significance.

Setting a custom user agent in Rails

Inside a Rails application you can set the user agent to the application name like this:

mechanize.user_agent = Rails.application.class.parent_name

Using a built-in user agent alias

To emulate a browser, use the Mechanize#user_agent_alias= method to specify one of the built-in user agent aliases. For example:

mechanize.user_agent_alias = 'Mac Safari'

You could also use the Array#sample method to select a random alias like this:

aliases = ['Linux Firefox', 'Windows Chrome', 'Mac Safari']

mechanize.user_agent_alias = aliases.sample

Looking for more information about Ruby Mechanize? Read the HOWTO scrape websites with Ruby & Mechanize guide, or grab yourself a copy of the Ruby Mechanize Handbook.

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