If you have an app that doesn't have any views (for example it only responds with JSON) you still may want to use excellent Kaminari gem for paginating big data sets. Unfortunately even when you work only with JSON and you don't need any views helpers, you will still get this warning:

[!]You should install `padrino-helpers' gem if you want
to use kaminari's pagination helpers with Sinatra.
[!]Kaminari::Helpers::SinatraHelper does nothing now...

so to get rid of this, you have to add:

gem 'padrino-helpers'

to your Gemfile (even when you don't need it).

Luckily, there's a better way to do this. Add Kaminari to your Gemfile that way:

gem 'kaminari', require: %w( kaminari kaminari/hooks )

and then, either create a config/initializers/kaminari.rb or directly in your app.rb put this:

# Initialize the Kaminari gem

This will initialize Kaminari without requesting padrino-helpers.