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An easy, Ruby way to use the Pwned Passwords API.

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An easy, Ruby way to use the Pwned Passwords API.

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API docs | GitHub repo

Table of Contents


Troy Hunt's Pwned Passwords API V2 allows you to check if a password has been found in any of the huge data breaches.

is a Ruby library to use the Pwned Passwords API's k-Anonymity model to test a password against the API without sending the entire password to the service.

The data from this API is provided by Have I been pwned?. Before using the API, please check the acceptable uses and license of the API.

Here is a blog post I wrote on how to use this gem in your Ruby applications to make your users' passwords better.


Add this line to your application's Gemfile:

gem 'pwned'

And then execute:

$ bundle

Or install it yourself as:

$ gem install pwned


There are a few ways you can use this gem:

  1. Plain Ruby
  2. Rails
  3. Rails and Devise

Plain Ruby

To test a password against the API, instantiate a

object and then ask if it is
password ="password")
#=> true
#=> 3303003

You can also check how many times the password appears in the dataset.

password ="password")
#=> 3303003

Since you are likely using this as part of a signup flow, it is recommended that you rescue errors so if the service does go down, your user journey is not disturbed.

  password ="password")
rescue Pwned::Error => e
  # Ummm... don't worry about it, I guess?

Most of the times you only care if the password has been pwned before or not. You can use simplified accessors to check whether the password has been pwned, or how many times it was pwned:

#=> true
#=> 3303003


You can set http request options to be used with

when making the request to the API. These options are documented in the
. The
option defines defines HTTP headers. These headers must be string keys.
password ="password", headers: { 'User-Agent' => 'Super fun new user agent' }, read_timeout: 10)

ActiveRecord Validator

There is a custom validator available for your ActiveRecord models:

class User < ApplicationRecord
  validates :password, not_pwned: true
  # or
  validates :password, not_pwned: { message: "has been pwned %{count} times" }


You can change the error message using I18n (use

to interpolate the number of times the password was seen in the data breaches):
      not_pwned: has been pwned %{count} times
      pwned_error: might be pwned


If you are ok with the password appearing a certain number of times before you decide it is invalid, you can set a threshold. The validator will check whether the

is greater than the threshold.
class User < ApplicationRecord
  # The record is marked as valid if the password has been used once in the breached data
  validates :password, not_pwned: { threshold: 1 }

Network Error Handling

By default the record will be treated as valid when we cannot reach the servers. This can be changed with the

validator parameter:
class User < ApplicationRecord
  # The record is marked as valid on network errors.
  validates :password, not_pwned: true
  validates :password, not_pwned: { on_error: :valid }

The record is marked as invalid on network errors

(error message "could not be verified against the past data breaches".)

validates :password, not_pwned: { on_error: :invalid }

The record is marked as invalid on network errors with custom error.

validates :password, not_pwned: { on_error: :invalid, error_message: "might be pwned" }

We will raise an error on network errors.

This means that record.valid? will raise Pwned::Error.

Not recommended to use in production.

validates :password, not_pwned: { on_error: :raise_error }

Call custom proc on error. For example, capture errors in Sentry,

but do not mark the record as invalid.

validates :password, not_pwned: { on_error: ->(record, error) { Raven.capture_exception(error) } } end

Custom Request Options

You can configure network requests made from the validator using

(see Net::HTTP.start for the list of available options). In addition to these options, HTTP headers can be specified with the
key, e.g.
  validates :password, not_pwned: {
    request_options: { read_timeout: 5, open_timeout: 1, headers: { "User-Agent" => "Super fun user agent" } }

Using Asynchronously

You may have a use case for hashing the password in advance, and then making the call to the Pwned api later (for example if you want to enqueue a job without storing the plaintext password):

hashed_password = Pwned.hash_password(password)
# some time later, request_options).pwned?


If you are using Devise I recommend you use the devise-pwned_password extension which is now powered by this gem.

Command line

The gem provides a command line utility for checking passwords. You can call it from your terminal application like this:

$ pwned password
The password has been found in public breaches 3645804 times.

If you don't want the password you are checking to be visible, call:

$ pwned --secret

You will be prompted for the password, but it won't be displayed.

How Pwned is Pi?

@daz shared a fantastic example of using this gem to show how many times the digits of Pi have been used as passwords and leaked.

require 'pwned'

PI = '3.14159265358979323846264338327950288419716939937510582097494459230781640628620899862803482534211706798214808651328230664709384460955058223172535940812848111'

for n in 1..40 password = PI[0..(n + 1)] str = [ n.to_s.rjust(2) ] str << (password.pwned? ? '😑' : 'πŸ˜ƒ') str << password.pwned_count.to_s.rjust(4) str << password.password

puts str.join ' ' end

The results may, or may not, surprise you.

 1 😑   16 3.1
 2 😑  238 3.14
 3 😑   34 3.141
 4 😑 1345 3.1415
 5 😑 2552 3.14159
 6 😑  791 3.141592
 7 😑 9582 3.1415926
 8 😑 1591 3.14159265
 9 😑  637 3.141592653
10 😑  873 3.1415926535
11 😑  137 3.14159265358
12 😑  103 3.141592653589
13 😑   65 3.1415926535897
14 😑  201 3.14159265358979
15 😑   41 3.141592653589793
16 😑   57 3.1415926535897932
17 😑   28 3.14159265358979323
18 😑   29 3.141592653589793238
19 😑    1 3.1415926535897932384
20 😑    7 3.14159265358979323846
21 😑    5 3.141592653589793238462
22 😑    2 3.1415926535897932384626
23 😑    2 3.14159265358979323846264
24 πŸ˜ƒ    0 3.141592653589793238462643
25 😑    3 3.1415926535897932384626433
26 πŸ˜ƒ    0 3.14159265358979323846264338
27 πŸ˜ƒ    0 3.141592653589793238462643383
28 πŸ˜ƒ    0 3.1415926535897932384626433832
29 πŸ˜ƒ    0 3.14159265358979323846264338327
30 πŸ˜ƒ    0 3.141592653589793238462643383279
31 πŸ˜ƒ    0 3.1415926535897932384626433832795
32 πŸ˜ƒ    0 3.14159265358979323846264338327950
33 πŸ˜ƒ    0 3.141592653589793238462643383279502
34 πŸ˜ƒ    0 3.1415926535897932384626433832795028
35 πŸ˜ƒ    0 3.14159265358979323846264338327950288
36 πŸ˜ƒ    0 3.141592653589793238462643383279502884
37 πŸ˜ƒ    0 3.1415926535897932384626433832795028841
38 πŸ˜ƒ    0 3.14159265358979323846264338327950288419
39 πŸ˜ƒ    0 3.141592653589793238462643383279502884197
40 πŸ˜ƒ    0 3.1415926535897932384626433832795028841971


After checking out the repo, run

to install dependencies. Then, run
rake spec
to run the tests. You can also run
for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run

bundle exec rake install
. To release a new version, update the version number in
, and then run
bundle exec rake release
, which will create a git tag for the version, push git commits and tags, and push the
file to


Bug reports and pull requests are welcome on GitHub at This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.


The gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the Pwned project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.

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