Flipper Cloud

Flipper UI

Flipper UI is a self-hosted web interface that gives you access to the basics. It's simple and pretty.


Viewing list of features:


Viewing an individual feature:



Add this line to your application's Gemfile:

gem 'flipper-ui'

And then execute:

$ bundle

Or install it yourself as:

$ gem install flipper-ui



Given that you've already initialized Flipper as per the flipper readme, you can mount Flipper::UI to a route of your choice:

# config/routes.rb
YourRailsApp::Application.routes.draw do
  mount Flipper::UI.app(Flipper) => '/flipper'

If you'd like to lazy load flipper, you can instead pass a block to initialize it:

# config/routes.rb
YourRailsApp::Application.routes.draw do
  flipper_block = lambda {
    # some flipper initialization here, for example:
    adapter = Flipper::Adapters::Memory.new
  mount Flipper::UI.app(flipper_block) => '/flipper'


You almost certainly want to limit access when using Flipper::UI in production.

Basic Authentication via Rack

The Flipper::UI.app method yields a builder instance prior to any predefined middleware. You can insert the Rack::Auth::Basic middleware, that'll prompt for a username and password when visiting the defined (i.e., /flipper) route.

# config/routes.rb

flipper_app = Flipper::UI.app do |builder|
  builder.use Rack::Auth::Basic do |username, password|
    # Verify credentials
mount flipper_app, at: '/flipper'
Route Constraints

It is possible to use routes constraints to limit access to routes:

# config/routes.rb

flipper_constraint = lambda { |request| request.remote_ip == '' }
constraints flipper_constraint do
  mount Flipper::UI.app => '/flipper'

Another example is to use the current_user when using a gem-based authentication system (i.e., warden or devise):

# initializers/admin_access.rb

class CanAccessFlipperUI
  def self.matches?(request)
    current_user = request.env['warden'].user
    current_user.present? && current_user.respond_to?(:admin?) && current_user.admin?

# config/routes.rb

constraints CanAccessFlipperUI do
  mount Flipper::UI.app(Flipper) => '/flipper'


Minimal example for Rack:

# config.ru

require 'flipper/ui'

adapter = Flipper::Adapters::Memory.new
flipper = Flipper.new(adapter)

run Flipper::UI.app(flipper) { |builder|
  builder.use Rack::Session::Cookie, secret: "something long and random"

The key is that you need to have sessions setup. Rails does this for you, so this step isn't necessary, but for standalone rack, you'll need it. Without sessions setup, you will receive a Runtime error like:

RuntimeError: you need to set up a session middleware *before* Rack::Protection::RemoteToken.

See examples/ui/basic.ru for a more full example


Flipper UI can be customized via configure, which yields a configuration instance.


We can associate a description for each feature by providing a descriptions source:

Flipper::UI.configure do |config|
  config.descriptions_source = ->(keys) do
    # descriptions loaded from YAML file or database (postgres, mysql, etc)
    # return has to be hash of {String key => String description}

  # Defaults to false. Set to true to show feature descriptions on the list
  # page as well as the view page.
  # config.show_feature_description_in_list = true

Descriptions show up in the UI like so:



Flipper UI can display a banner across the top of the page. The banner_text and banner_class can be configured by using the Flipper::UI.configure block as seen below.

Flipper::UI.configure do |config|
  config.banner_text = 'Production Environment'
  config.banner_class = 'danger'

By default the environment is set to an empty string so no banner will show. If you wish to customize the look of the banner, you can set banner_class to one of the bootstrap color classes: primary, secondary, success, danger, warning, info, light, or dark. The default banner_class is danger.

The above configuration results in:


Fun mode

By default, Flipper UI displays a videoclip when there are no flags. The fun mode can be configured by using the Flipper::UI.configure block as seen below.

Flipper::UI.configure do |config|
  config.fun = false

Import / Export

Flipper UI supports importing and exporting features. This is useful for sharing features between environments or backing up features.

  • To export a backup file, click Download. This file can be shared with other developers or used to restore features to another environment. You can also import this file into Flipper Cloud for easy migration.
  • To import a backup file, choose it from the Import form and click Import.

Import and Export

Start flipping features with Flipper Cloud to get support, audit history, finer-grained permissions, multi-environment sync, and all of your projects in one place.

Prefer our open source Cloudless option? You can also choose from several tiers to sponsor Flipper on GitHub.