New sources are italicized. Sources that have been removed from 2021 list are at the bottom.
If you have any additional sites that you please leave them in the comments.
Compare Flight Theoretical Redemption Costs
Awardhacker.com shows theoretical saver level award pricing between two cities, this is based on flight schedules; good
http://www.milez.biz shows theoretical save level award pricing, but also contains helpful routing tips, 15 searches per month free then paid
https://www.travelcodex.com/award-maximizer/ shows theoretical saver level award pricing between two airports, pricing is based on award chart, not as accurate for distance-based charts
http://wandr.me/Award-Search/Avios-Map/tool to see what routes you can book cheap Avios distance awards from, please note this outdated and there are no more 4500 mile awards in the US, RIP
Resources to Find Award Availability
https://seats.aero/Last minute award flights a limited number of programs and select airports, can set alerts, free, dev active in this community (new name)
https://straighttothepoints.co/Economy flights are free, business is paid alerts. A little different than some of the others give dates and it gives destinations.
https://www.seatspy.com/paid resource, can search up to a year at a time, fewer airlines than some other tools. Nonstop only; good to find availability on a specific route with flexible dates.
https://awardlogic.com/lets you search for free and tells you the price, but blocks out the program, you can often figure it out and it lets you know simply if there is a cheap option. Full source is paid. Good for specific dates with 20+ airlines. I often use the free version to see if there is any base award availability and since it gives Chase Portal pricing I get an idea of the cash price too.
https://www.cowtool.com/Searches Air Canada (Star Alliance) award availability on multiple dates, origins, and destinations, free, but requires registration
https://rewardflightfinder.com/search for British Airways flights between two destinations, free account gives year-long view with number of seats and miles price per class, nice formatting
https://awardnexus.com/ paid resource, does do a good job, with Flyer Talk login can do some searches, searches up to 7 days at a time
https://www.expertflyer.com shows award and upgrade availability, free trial, paid, owned by TPG’s parent company.
http://www.kvstool.com/ like ExpertFlyer, but less user-friendly and a little more powerful, paid, recently many complaints of not getting login information after paying, does not appear to be dead, but I would not use it
https://openhotelalert.com/ look for specific room class availability. Good site for looking for hotel award availability. Can do general hotel or specific room.
https://flightdelay.etherisc.com/#/blockchain based trip delay insurance (it is having a hard time pulling up flights when I am testing now, but was working fine a month ago)
https://www.foxtrotdash.com/dashboard to can track points and award redemptions, it can also suggest trip options based on your points (you input the destination)