I use this. http://www.agarserv.com/
it's credit based on some server modifications, but you can however do minor, just read below the boxes before ticking in the modification you want.
Gaming Discussions
Agar.io private server
Submitted by Castiel, 18-01-2016, 12:10 AM, Thread ID: 17042
Thread Closed
RE: Agar.io private server 18-01-2016, 12:14 AM This post was last modified: 18-01-2016, 12:15 AM by Deleted_3747 #2
18-01-2016, 12:14 AM
#2 This post was last modified: 18-01-2016, 12:15 AM by Deleted_3747