Is there a fingerprint reader api/sdk?

Did you take a look at the BioAPI consortium site? There's a library for linux over at Google code.

There's also libchipcard, but it doesn't mention fingerprint readers, only smart cards.

Hope that helps.

Digitalpersona has a free SDKs both for windows and linux. http://www.digitalpersona.com/products/developer.php

I dont know if there are costs for deploying with their SDKs.

(Actually it appears they don't charge per machine/user licensing.)

There is no standard API for reading fingerprint data as far as I'm aware since it is a fairly new field and there's no standard way of doing it. Each manufacturer will provide their own API for reading the hardware. The API could just be IO specification to the hardware and there's no library whatsoever, which makes things a bit trickier. This is down to two factors. The first is that finger print readers are used in many applications - custom hardware, embedded systems through to PC authentication and beyond. Providing software for all those different systems would not be viable from the manufacturers point of view. Secondly, each manufacturer uses a different approach to reading and processing the captured images which would make a common API problematic.

It's an old question, but I bumped into it while researching the topic.

I did find a free library for Linux - libfprint