The simplest, most flexible, most standards-compliant pagination gem there is. Pairs nicely with begriffs/angular-paginate-anything.

class ApplicationController < ActionController::Base
  include CleanPagination

  # Using activemodel
  def index
    max_per_page = 100

    paginate Bla.count, max_per_page do |limit, offset|
      render json: Bla.limit(limit).offset(offset)
    end
  end

  # Using some custom data
  def numbers
    paginate Float::INFINITY, 100 do |limit, offset|
      render json: (offset...offset+limit).to_a
    end
  end
  
  # Using optional settings
  def options
    begin
      paginate Foo.scope.count, max_per_page, allow_render: false, raise_errors: true do |limit, offset|
        respond_with Foo.scope.limit(limit).offset(offset)
      end
    rescue RangeError
      render json: { error: { message: "invalid pagination range" } }
    end
  end
end

• HTTP Content-Type agnoticism. Information about total items, selected ranges, and next- previous-links are sent through headers. It works without modifying your API payload in any way.
• Graceful degredation. Both client and server specify the maximum page size they accept and communication gracefully degrades to accomodate the lesser.
• Expressive retrieval. This approach, unlike the use of per_page and page parameters, allows the client to request any (possibly unbounded) interval of items.
• Semantic HTTP. Built in strict conformance to RFCs 2616 and 5988.

To prevent this gem from rendering while still allowing it to set headers and response codes, pass allow_render: false to paginate. This may be used to avoid DoubleRenderError situations.

To handle the invalid request range condition in your app, pass the raise_errors: true option. This will raise a RangeError which you can rescue (and thus control what is rendered). Headers will still be set.

[TODO: explain what the headers mean.] Until this is written you can consult the tests for an idea how it works, or use a client that is compatible, such as begriffs/angular-paginate-anything.