You can say this in helpers like link_to and content_tag:

= link_to 'Label', root_url, :data => { :foo => 'bar', :bam => 'baz' }

UI/UX Design by

We make sure that your target audience has the best possible experience with your digital product. You get:

• Design tailored to your audience
• Proven processes customized to your needs
• An expert team of experienced designers

Read more Show archive.org snapshot

This will produce:

<a href="/" data-foo="bar" data-bam="baz">Label</a>

Only works in Rails 3. In Rails 2 you do

= link_to 'Label', root_url, 'data-foo' => 'bar', 'data-bam' => 'baz' }