Wow, 1.4 million daily clicks is insane!
For the download niche with that kind of traffic, you've got some really good options beyond popunders.
Native ads work really well in download niches.
Companies like MGID, Taboola, and Outbrain pay way better than popunders.
You can integrate them naturally into your content without being too aggressive.
Affiliate programs for software downloads could be huge for you.
Companies like Adobe, Microsoft, and other software vendors have affiliate programs.
With your traffic volume, even a 1% conversion rate would be massive.
Display advertising with Google AdSense or Media.net might work better than you think.
The download niche usually has decent CPM rates.
You could easily be making $5-10k per day with display ads at that traffic level.
Sponsored content and reviews could be another goldmine.
Software companies would kill to get exposure to 1.4 million daily visitors.
You could charge $500-2000 per sponsored post.
Email capture and email marketing.
With that much traffic, you could build a massive email list.
Then promote software deals and affiliate offers to your list.
Why didn't CPA work for you?
Was it the offers you were promoting or the way you were implementing them?
With that traffic, you should be able to make CPA work if you target the right offers.
What kind of download content are you publishing?
That would help me suggest more specific monetization strategies.