Is it possible to add a countdown timer on my sales page?
There are a few tools to consider:
1. MotionMail
This tool will create a countdown timer, and give you embed code. You can add it to your website, or your newsletter... anything that allows embed code. It's free and looks great.
It can be customized to match your own brand, like this:
Learn More: https://MotionMail.com
2. ProTimer
The free version allows up to 10,000 views and 7 design options. They also have a nice looking upgrade that will work with evergreen automation funnels (for example: include a promotion for the 1st 3 days someone is on your email list). Their paid plans start at $5/month
Learn More: http://makedreamprofits.com/pt/