A few years ago I made a post about different websites for your submissions (post can be found here). One of the websites is no longer free, Duotrope.
Duotrope was (and presumably still is) a wonderful website for writers. Not only was it searchable for open markets, it had a wonderful search engine for putting in specifics such as pay rate or whether or not said markets accept reprints, it was also a database where you could store your submissions. Sadly Duotrope became a pay service, I believe early this year (feel free to correct me if I'm wrong).
There is nothing wrong with Duotrope charging for their service. They have almost 5,000 markets listed and help you keep track of where you are sending your stuff. Besides it doesn't actually cost that much, $50 a year. If you are on staff somewhere or are regularly selling stuff to pro and semi-pro markets, bite the bullet and get a membership. Or you can always ask an understanding family member for a birthday/Christmas present in that amount. For the service they offer it is a really good deal.
However, if your writing income makes up less than 5% of your yearly income (like mine does) you'll want to know where else to go to submit your stuff. I've used Ralan's for years.
I check it every day I'm submitting. You can join his Facebook that he updates frequently. Ralan's is nice. It has led to quite a few acceptances for me over the years (and I've paid back the favor by donating some money to him). But it doesn't have the nifty search engine or tracking abilities of Duotrope.
Recently I kind of bumbled along and found The Submission Grinder.
The Submission Grinder is a free alternative to Duotrope. Not only does it work in a very similar manner, you can actually import your information from Duotrope into The Submission Grinder. The Submission Grinder only has about 2,500 markets listed at the moment but you can help by dropping emails to them about markets you've found and if you have a magazine get it listed.
Is it perfect? No. But it is free and it is pretty cool. And it is one more tool to help you get your stuff out into the world.