Once of the common things needed in webapps is to escape html.
Most frameworks acknowledge that need, and include helpers to do it for you. Sinatra isn’t that kind of framework. If you want it, it’s easy to wire in, but you need to ask.
Luckily, Sinatra is easily convinced, and will point you to it’s close friend, Rack.
helpers do include Rack::Utils alias_method :h, :escape_html end
These few lines will include all of Rack::Utils (a few methods), and then rename one of them to match what Rails and Merb (and others) provide.
Now in your views, you can easily call escape html like:
<%= h myUnsafeContent %>