NOTE Code contributions are most welcome see
How-to-contribute-translation
Join-the-project-as-a-developer
Some means to donate once (paypal) or sponsor as a patron via patreon.com have now been added see the top right 
button on most web site pages
This is really a great software，works well even for 400M files,butter smoooth. thanx sooo much
Is there any way to donate? I was looking in the software and this website, but havnt got.
Alipay will be better…
Thanx again DEVELOPER!
[Moderator’s note: This was the official response in 2017, but has changed now.]
Thanks for the offer but we don’t accept donations.
I have used this pgm for several YEARS! I want to contribute …
If you’re a developer or designer and want to contribute code or icons etc. I’m sure the dev will appreciate it.
For monetary contributions you can read the dev’s official response above.
Any way to donate? Sumatra is one of my favorite programs, and I recommend it to all my college student friends. I would love to be able to support the development of this excellent software .
Thanks for the offer, @Sam_S, but regarding monetary contributions you can read the dev’s official response above.
IMO code (especially) and icon contributions would be great however since this project really needs support to fix the numerous open GitHub issues, add new features etc.
You may note from the new heading that there is now the opportunity to support / donate if you wish to.
I’d like to contribute monthly via Patreon for this great app, but I can only afford $1/month. Would there be any interest in creating an additional lower tier? I try to contribute something monthly to all the projects I use and it adds up.
Thanks