My understanding of the gift tax is that the donor has to pay the tax, but up to a limit they don't have to pay tax.
I'm a developer. Suppose I offer my software/libraries/blog for free on my site and have the option to donate via PayPal, Patreon, or whatever. Is that money considered a gift and therefore tax free?
Donations, particularly those in the context of you providing a free service (software, libraries, etc.) are a notable grey area in tax code.
Simply naming a button "Donate" doesn't necessarily classify the money transfer as a "gift". The IRS can decide that it's money you're being paid to continue your excellent work/service, making it taxable income (unless you're a registered non-profit organization).
In the instance of Patreon, and many other crowd-funding services, you're providing a certain level of "service" for each tier of donations (such as early access or something, I'm not sure what you're offering), which means they're receiving consideration for their donations, which most likely makes it fall into taxable income (again, unless you're a registered non-profit organization).
State tax law is even more convoluted, and you should consult your tax professional for clarification on your specific situation.
"Donate" buttons are meaningless with regards to taxes. This is payment for something you provided, and you cannot claim that you've received a gift.
Any money you receive in this way is payment for your software. Remember, for gifts - no consideration should have been provided to the donor. Anything for which a consideration was provided - cannot be a gift. In your case the consideration is the software, and it's value is the amount you were paid. Since every person can decide how much to pay you on his own - any payment is for the software, not a gift.
Any money you get is taxable to you, and you cannot claim it as "gifts" without exposing yourself to risks of making fraudulent claims.
Consult a licensed tax adviser (EA/CPA licensed in your State) for a qualified tax advice.
