libpostal is a pretty incredible open source project, but addresses are so complicated and nuanced that depending on what you’re doing, it might not be able to keep up. I work for a real estate tech company where we do a lot of address parsing and we had to move away from it because it’s just not quite powerful enough to handle all of the edge cases you find in US addresses. Right now we use SmartyStreets because their address parser is a bit better for our use case. Libpostal is a great general purpose library but depending on what level of accuracy you need, you might have to look for alternatives.

I spent time trying to use libpostal and build USPS address normalization rules on top of it but there are so many edge cases it was more cost effective to just purchase a solution from a vendor.

That is not to take away from this project — it’s quite good for a broad set of addresses across the world — but for narrow use cases such as ours it just couldn’t quite cut it.