Soul Mate Find is geared toward people who are trying to find life partners.While using the site is free, it does require "credits" which you earn by logging in every day or by referring friends to the site.Both sites let people browse ads for free, but they must pay if they want to respond to these ads or read and reply to messages they receive.
A lot of dating sites that were free at one point are no longer free to use now; for example, Match and Lava Life.
This site also has a mobile app available for free.
Plenty of Fish works to set you up with other members you're likely to be compatible with based on a chemistry test.
You'll also get free relationship coaching via blogs and a popular message board.
This site is for people looking for dates and also for casual flings. Date is another one that uses an algorithm to match users.