What is Duckduckgo.com?
Duckduckgo.com is a search engine that emphasizes user privacy. Driven its first principle "search without tracking" it has been gaining lots of users over the last few years.
On February of 2019, DuckDuckGo reached the milestone of 1 billion searches in a month, still far away from more famous search engines like Google or Bing, but still a decent amount, especially considering that those numbers keep growing.

Duckduckgo.com / referral in Google Analytics
Some Google Analytics users mistake DuckDuckGo as referral spam, probably because of its unusual name. However, as you already know it is a valid source.
The problem is that despite being a search engine, Google Analytics will assign it as one of the following referrals instead of organic traffic.
- duckduckgo.com / referral
- r.duckduckgo.com / referral

What is r.duckduckgo.com?
r.duckduckgo.com is an internal redirection to prevent the browser to pass user information, is a measure applied by the search engine to protect the privacy of the user by removing the search term of the query.
When this measure is applied, you will see r.duckduckgo.com / referral in your reports. Apart from that it is exactly the same as the source without the letter "r".
Reassign Duckduckgo.com and r.duckduckgo.com referrals to organic traffic
Google Analytics has a built-in option to include additional search engines besides the ones GA already considers organic. However, for some reason that won't work with DuckDuckgo
So to move duckduckgo to the right place you will need to create a filter:
- Go to your Google Analytics Admin tab and select Filters
- Click on +Add Filter and enter an appropriate name for the filter like "Google Android"
- Configure the filter:
- Filter Type: Custom > Advanced
- Field A > Extract A (copy the expression below)
duckduckgo|ecosia\.org|search\.aol\.org|dogpile\.com - Once everything is set, save your filter
How to index your website duckduckgo.com?
Now that you know that DuckDuckGo is a fast growing search engine you might want to know how to get indexed by them.
However, as for now (January 2019), there is no option to send a sitemap directly to duckduckgo.com, as explained on their forum:
DuckDuckGo gets its results from over one hundred sources, including DuckDuckBot (our own crawler), crowd-sourced sites (like Wikipedia, which are stored in our own index), Yahoo! (through BOSS), Yandex, Yelp, and Bing. Once your web site has been indexed byour sources it will appear in DuckDuckGo searches.
DuckDuckGo.com gets its results from multiple sources, including DuckDuckBot, and crowdsourcing from Wikipedia, Yandex, Yelp, and Bing.

Extra: DuckDuckgo.com features
As I mentioned before duckduckgo is an original search engine. These are some of its features:
- Instant Answers for many things like time and weather. For example, If you type weather in the search bar you will get information about today's weather and the next days of your region without needing to go to another page.
Or one of my favorites, recipes, if you type avocado recipe you'll get a list of recommendations for recipes with avocado as an ingredient. This also works with many other Instant Answers like movies and music.

- !Bangs: if you type !yt movie trailers it will take you to youtube and show you the results for "movie trailers", or if you type !a tv will search for Televisions in Amazon. These shortcuts are called !bangs and there are many, for example:
- Amazon: !a
- Google maps: !m
- Facebook: !fb

- Fully customizable; you can change the theme, search preference you can event turn off the few ads it shows.

Conclusion
- Google Analytics: Despite its odd name duckduckgo.com is valid traffic, however, it shouldn't be classified as a referral because it is a search engine, so you need to create a filter so it shows as organic traffic.
- SEO (site indexing): There is no direct way to get indexed by DuckDuckto, instead you will need to send your sitemap to other search engines, and eventually duckduckgo will crawl your site.
- For users: duckduckgo.com is an excellent choice for those people that worry about their privacy or simply want a better-looking interface while browsing in the evenings.