diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
index 0000000..919b3b4
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,83 @@
+# Proxy Fetcher Changelog
+
+Reverse Chronological Order:
+
+## `0.4.0` (2017-08-26)
+
+* Support operations with multiple providers
+* Refactor filtering
+* Small bugfixes
+* Documentation
+
+## `0.3.1` (2017-08-24)
+
+* Remove speed from proxy (no need to)
+* Extract proxy validation from the HTTPClient to separate class
+* Make proxy validator configurable
+* Refactor proxy validation behavior
+* Refactor Proxy object (OpenStruct => PORO, url / uri methods, etc)
+* Optimize proxy list check with threads
+* Improve proxy_fetcher bin
+
+## `0.3.0` (2017-08-21)
+
+* Proxy providers refactoring
+* Proxy object refactoring
+* Specs refactoring
+* New providers
+* Custom HTTP client
+* Configuration improvements
+* Proxy filters
+
+## `0.2.5` (2017-08-17)
+
+* Configurable HTTPClient
+* Fix errors handling
+
+## `0.2.3` (2017-08-10)
+
+* Fix broken providers
+* Add new providers
+* Docs
+
+## `0.2.2` (2017-07-20)
+
+* Code & specs refactoring
+
+## `0.2.1` (2017-07-19)
+
+* New proxy providers
+* Bugfixes
+
+## `0.2.0` (2017-07-17)
+
+* New proxy providers
+* Custom providers
+* Network errors handling
+* Specs refactorirng
+
+## `0.1.4` (2017-05-31)
+
+* Code & specs refactoring
+* Add `speed` to `Proxy` object
+* Docs
+
+## `0.1.3` (2017-05-25)
+
+* Proxy list management with `ProxyFetcher::Manager`
+
+## `0.1.2` (2017-05-23)
+
+* HTTPS proccesing
+* `Proxy` object sugar
+* Specs improvements
+* Docs improvements
+
+## `0.1.1` (2017-05-22)
+
+* Configuration (timeouts)
+* Documentation
+
+## `0.1.0` (2017-05-19)
+
+* Initial release
\ No newline at end of file
diff --git a/CODE_OF_CONDUCT.md b/CODE_OF_CONDUCT.md
new file mode 100644
index 0000000..10513ca
--- /dev/null
+++ b/CODE_OF_CONDUCT.md
@@ -0,0 +1,46 @@
+# Contributor Covenant Code of Conduct
+
+## Our Pledge
+
+In the interest of fostering an open and welcoming environment, we as contributors and maintainers pledge to making participation in our project and our community a harassment-free experience for everyone, regardless of age, body size, disability, ethnicity, gender identity and expression, level of experience, nationality, personal appearance, race, religion, or sexual identity and orientation.
+
+## Our Standards
+
+Examples of behavior that contributes to creating a positive environment include:
+
+* Using welcoming and inclusive language
+* Being respectful of differing viewpoints and experiences
+* Gracefully accepting constructive criticism
+* Focusing on what is best for the community
+* Showing empathy towards other community members
+
+Examples of unacceptable behavior by participants include:
+
+* The use of sexualized language or imagery and unwelcome sexual attention or advances
+* Trolling, insulting/derogatory comments, and personal or political attacks
+* Public or private harassment
+* Publishing others' private information, such as a physical or electronic address, without explicit permission
+* Other conduct which could reasonably be considered inappropriate in a professional setting
+
+## Our Responsibilities
+
+Project maintainers are responsible for clarifying the standards of acceptable behavior and are expected to take appropriate and fair corrective action in response to any instances of unacceptable behavior.
+
+Project maintainers have the right and responsibility to remove, edit, or reject comments, commits, code, wiki edits, issues, and other contributions that are not aligned to this Code of Conduct, or to ban temporarily or permanently any contributor for other behaviors that they deem inappropriate, threatening, offensive, or harmful.
+
+## Scope
+
+This Code of Conduct applies both within project spaces and in public spaces when an individual is representing the project or its community. Examples of representing a project or community include using an official project e-mail address, posting via an official social media account, or acting as an appointed representative at an online or offline event. Representation of a project may be further defined and clarified by project maintainers.
+
+## Enforcement
+
+Instances of abusive, harassing, or otherwise unacceptable behavior may be reported by contacting the project team at bulajnikita@gmail.com. The project team will review and investigate all complaints, and will respond in a way that it deems appropriate to the circumstances. The project team is obligated to maintain confidentiality with regard to the reporter of an incident. Further details of specific enforcement policies may be posted separately.
+
+Project maintainers who do not follow or enforce the Code of Conduct in good faith may face temporary or permanent repercussions as determined by other members of the project's leadership.
+
+## Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant][homepage], version 1.4, available at [http://contributor-covenant.org/version/1/4][version]
+
+[homepage]: http://contributor-covenant.org
+[version]: http://contributor-covenant.org/version/1/4/
diff --git a/README.md b/README.md
index 86024fd..b88276f 100644
--- a/README.md
+++ b/README.md
@@ -75,12 +75,17 @@ manager.proxies
  #=> []
 ```
 
-If you wanna clean current proxy list from some dead servers that does not respond to the requests, than you can just call `cleanup!` method:
+If you want to clean current proxy list from the dead servers that does not respond to the requests, than you can just call `cleanup!` method:
 
 ```ruby
 manager.cleanup! # or manager.validate!
 ```
 
+In order to increase the speed of this operation proxy list validation is performed using Ruby threads.
+By default, gem creates a pool with 10 threads, but you can increase this number by passing threads pool
+size to the `#cleanup!` (or `#validate!`) method: `manager.validate!(50)`. In that case ProxyFetcher will
+process all the fetched proxies in group of 50 threads.
+
 Get raw proxy URLs as Strings:
 
 ```ruby
diff --git a/lib/proxy_fetcher/providers/base.rb b/lib/proxy_fetcher/providers/base.rb
index c5afc97..4e307d9 100644
--- a/lib/proxy_fetcher/providers/base.rb
+++ b/lib/proxy_fetcher/providers/base.rb
@@ -23,8 +23,10 @@ def fetch_proxies!(filters = {})
 
       # Loads HTML document with Nokogiri by the URL combined with custom filters
       def load_document(url, filters = {})
+        raise ArgumentError, 'filters must be a Hash' if filters && !filters.is_a?(Hash)
+
         uri = URI.parse(url)
-        uri.query = URI.encode_www_form(filters) if filters.any?
+        uri.query = URI.encode_www_form(filters) if filters && filters.any?
 
         Nokogiri::HTML(ProxyFetcher.config.http_client.fetch(uri.to_s))
       end
diff --git a/proxy_fetcher.gemspec b/proxy_fetcher.gemspec
index 029879c..7e3c94f 100644
--- a/proxy_fetcher.gemspec
+++ b/proxy_fetcher.gemspec
@@ -5,7 +5,7 @@ require 'proxy_fetcher/version'
 Gem::Specification.new do |gem|
   gem.name = 'proxy_fetcher'
   gem.version = ProxyFetcher.gem_version
-  gem.date = '2017-08-21'
+  gem.date = '2017-08-26'
   gem.summary = 'Ruby gem for dealing with proxy lists from different providers'
   gem.description = 'This gem can help your Ruby application to make HTTP(S) requests ' \
                     'from proxy server by fetching and validating proxy lists from the different providers.'