Depends on the kind of conference you're looking for - but of the ones that catch my eye, Business Of Software USA is happening next week, Double Your Freelancing Conference at the end of the month, and Chaos Computer Congress at the end of the year in Germany.
* http://www.businessofsoftware.org/
* http://doubleyourfreelancing.com/conf/
* https://events.ccc.de/
I keep a bigger list of conferences I think would be of interest to indie developers (and freelancer / digital nomad types) at my Indie Conference website:
http://www.indieconference.com/