AARRR - metrics for Pirates

AARRR is a MongoDB backed ruby library that helps you track user lifecycle metrics for your web apps (with cohorts!).

The name comes from an acronym coined by Dave McClure that represents the five most important early metrics for any web startup: Acquisition, Activation, Revenue, Retention, and Referral.

A quick 5 min video:

Learn more about startup metrics for Pirates:


Why you should use AARRR:

AARRR is meant to quickly get you started and provide a framework for collecting and displaying data. It's goal is to help you learn what to measure, and quickly get results. It's long term goal is to really get you to think very hard about how to measure and track your users in order to provide actionable metrics about your web app.

While it has support for split testing, it's main goal is to provide macro metrics for your users. For more micro experiment driven metrics, you should check out tools such as Vanity and ABingo


  • Easily define custom cohorts (defaults to weekly cohorts). You can also define cohorts for specific deploys, or by traffic source.

  • Uses MongoDB for storing analytics (no schema needed, and super crazy fast writes)

  • Automatic configuration for Mongoid and MongoMapper users

  • Easily hooks into Devise (to capture User Acquisition event)

How to Install:

  • Add gem "aarrr" to your Gemfile and bundle

  • Run rails g aarrr:install to generate your initializer

  • If you'd like to customize the MongoDB connection (or if you aren't using Mongoid/MongoMapper, then edit config/initializers/aarrr.rb and set AARRR.connection to a valid Mongo::Connection. See the mongo gem tutorial for quick an easy instructions on how to set up a Mongo::Connection

AARRR is now set up, and will add an around filter to each request so it can handle user tracking. When a user first shows up at your site, we'll add in a "_utmarr" permanent cookie to them that uniquely identifies the user. You can configure this cookie in config/initializers/aarrr.rb.

How to add tracking

AARRR defines a helper method AARRR() that returns a "session" object. actually just an alias to AARRR::Session.new(). The session object's purpose is to define a user uniquely. All tracking events should be called from the session object

You can get a session in a few different ways:

# from an env hash (we'll pull out the right cookie tracking code)

# directly from a user (if they're already logged in)
# use this if you are doing tracking from model objects (you just need a reference to the user)

# pass in the tracking code directly

You should then save the session to cookie: AARRR(request.env).save(response)

Tracking vs Completion events

For each category of events, you can track multiple events leading up to the actual "completion" step for a category, use the option :in_progress => true


You'll probably want to track customer acquisition at the time of user signup. We can automatically hook into Devise so this event is triggered as soon as your user signs up.

If you'd rather define Acquisition events manually, just use:


To track the funnel leading up to the acquisition event, use:

AARRR(request.env).acquisition!(:opened_signup_popup, :in_progress => true)


Activation events should be tracked as soon as your user interacts "sucessfully" with your app. You'll need to define this for your own app, however if your app is built to do something specific then you should add an activation event whenever that thing happens.




Retention is defined by how often your user keeps coming back to the app. You can define retention rules separately in reports (e.g. 5 times in 2 months)



Referral should be triggered whenever someone gets someone else to sign up to your app. It's used to calculate a Virality coefficient which is. Learn more about the virality coefficient here.

Referrals are done in 2 parts. First you can track when someone decides to refer someone. This would be an "invite" link or something similar.

# generate a referral
referral_code = AARRR(request.env).sent_referral!(:sent => {email: "[email protected]"})

# email out the url with this referral code in the query param
# "?_a=x71n5"

# after accepting the code

When someone enters the site without an activated session and a referral code shows up, then we track the referral event as soon as the user signs up.


Track allows you to trigger multiple events at a time. (defaults to :activation event)

AARRR(request.env).track!(:built_page, :event_type => :activate, :in_progress => true)


Whenever you capture a dollar from user, then you should track that intake event.

# customer paid you 55.00

# can also pass in the cents

# it's also useful to pass in a unique code here (receipt / invoice number or something) so you don't double track someone's revenue
AARRR(request.env).revenue!(55.00, :unique => "x8175m1o58113")


Cohorts are ways to slice up reports so you can see the results for these 5 metrics for groups of specific users. Some useful examples are:

Date (by day, week, month)

slice up the metrics based on when users first came to your site (session creation). This is useful to see if what your building is actually improving your metrics

# assigns a cohort based on the week
AARRR.define_cohort :weekly do |user|
  user["created_at"].beginning_of_week.strftime("%B %d, %Y")

By Traffic Source

slice up the metrics based on where your users are coming from. This allows you to see what sources of traffic are most value and target your marketing efforts on these.

# assigns a cohort based on the traffic source
AARRR.define_cohort :source do |user|
  case user["referrer"]
  when /google.com/, /gmail.com/
  when /facebook.com/

By Keyword

slice up the users by the keyword (or groups of keyword) in order to classify users by market segment.

AARRR.define_cohort :keyword do |user, data|
  # define a `extract_keywords` method to pull out the keywords from the referrer url
  keywords = extract_keywords(user["referrer"])
  if keywords.include?("ruby") or keywords.include?("rails")

By gender (or other custom data attributes)

assuming you've captured it via AARRR(request.env).set_data(:gender => "m")

AARRR.define_cohort :gender do |user, data|
  if data["gender"].to_s.upcase == "M"
  elsif data["gender"].to_s.upcase == "F"

By Location

AARRR.define_cohort :location do |user, data|
  # define get_city_for method to get the city for a particular ip address

Split Testing

You can set up split testing by using:

AARRR.define_split :landing_redesign, :options => {
  :v1_layout => 0.9,
  :v2_layout => 0.1

To use these split tests, just add the following to your views:

AARRR(request.env).split?(:landing_redesign, :v1_layout) #=> true

The first argument is a reference to the split test that you defined in your initializer. The second argument is the split option to return.

This will attach the session with a randomly selected version of the split test and return whether it matches the second argument.

You can also just return the split option currently assigned to the user by using:

AARRR(request.env).split(:landing_redesign) #=> :v1_layout

Split test results can be accessed via the reports, and you can slice up the user metrics based on which users saw what split. People who saw neither splits will not be included in the results.

Ignored Cohorts

When you start seeing screwy data (spammers, seo, scrapers) you can selectively remove these people by configuring Ignored Cohorts. This just excludes data before running the report calculations.

This allows you to identify the AARRR users that are likely "spam" and removes them from most report results.

# pass it a mongo query that defines the users you want to ignore
AARRR.ignored_cohort :googlebot, "data.useragent" => /googlebot/

Pulling the Data out (generating reports)

AARRR provides some simple views that allow you to generate some basic reports. Reports are generated via a cron job rake aarrr:generate.

You can also generate the reports manually by running AARRR.generate!, however I'd advise you to run it via Resque or Delayed Job as it may take a long time to generate.

Once you have the reports, you can use the AARRR view helpers in order to render your reports to a web page.

Our report views probably aren't going to be exactly what you want, so we encourage you to cycle through the AAARR.report_results (returns the latest generated report results) and build up your own graphs and charts.

Data Model

This section describes how AARRR stores your data within the MongoDB collections (raw and reports).

Raw Events

AARRR tracks the raw metric data in a 2 main tables:

aarrr_users: tracks the unique identities of each user

  • _id: generated aarrr user id
  • user_id: optional tie in to your database's user_id (for drill down)
  • data: hash that stores any data that's passed for the user on creation. main use is for analyzing the cohort data
  • splits: hash that maps split testing rules to assigned splits for the user
  • cohorts: a hash that maps cohort rules with the results
  • ignore_reason: a string that represents the reason this user is ignored in reports
  • referrer: referrer url that user came from
  • ip_address: ip address for the user
  • last_event_at: date that the user last interacted with the site

aarrr_events: tracks each event that the user is engaged in

  • _id: generated aarrr event id
  • aarrr_user_id: id that maps event back to the aarrr users table
  • event_name: name for the event that was tracked
  • event_type: category of event type you are tracking
  • in_progress: true/false whether or not this event_type is in progress (not yet completed)
  • data: data that should be tracked along with the event
  • revenue: revenue the was generated on this event
  • referral_code: referral code that was generated for this event


... TBD ...