Serpentine Bold is a member of the Serpentine font family which is a completely commercial font and therefore isn't available for free. So please enjoy this list of great alternatives.
Several Great Options
The Serpentine font family is something I've written about before and I continue to enjoy the entire series. Unfortunately, the Serpentine Series is a commercial font at the time of writing this article and therefore isn't available anywhere reputable or safe for free at this time. While this may seem like kind of a bummer, I looked into a few free alternatives to Serpentine Bold that I guarantee you will like instead of the Serpentine Bold series.
Serpentine Bold definitely carries a unique feel with it. Some say that it does not pretend to mimic a hand-written style of typeface, instead stressing its digital, modern, almost sci-fi appearance and I agree with that. So what you will likely be looking for is a sci-fi or modern font that is somewhat blocky and very sharp rather than smooth and curvy.
I've put together a list of five fonts that share some characteristics to Serpentine Bold that I hope you will consider a suitable or better alternative.
(Click the font images for a larger preview.)
Aeromatics and Aeromatics Small Caps at DaFont.com
Aeromatics comes in two different versions, Aeromatics and Aeromatics Small Caps. The only difference is that Small Caps has lowercase letters whereas Aeromatics uses smaller uppercase letters for its lowercase font. This is a font that is quite a bit blockier and straighter than Serpentine Bold, but I feel it transfers the feel very well.
Black Hole BB Font
While it is thinner than Serpentine, it is a serif font which is important if you were searching for a sci-fi/modern font that needed to be a serif font. It is definitely sleek and a choice alternative.
Vibrocentric is the second closest to being Serpentine Bold. It's a thinner, sleeker serif font but still very practical and modern without being overly sci-fi.
Xirod is blocky, heavy, thick and very sci-fi and doesn't pretend to be anything else. This may not be your Serpentine Bold replacement but it's a fantastic alternative if you're will to go further with the sci-fi feel that the Serpentine Series is.
Zenith is probably the closest free font available to Serpentine Bold. It is a bold and heavy serif that does not pretend that it is handwritten. If you want Serpentine Bold but don't want to shell out the money to buy it? Zenith is your font.
All images are used for promotional and preview purposes.