<p>I need to read the user's fingerprint from my application.</p>

<p>What I really want is a simple SDK that works with a lot of inexpensive fingerprint readers but I can deal with something that works only with one specific model if that model is cheap and available worldwide.</p>

<p>And <strong>it has to be royalty-free</strong>, I can pay for a development license but if I have to pay for each installation I just can't use it.</p>

<p>What I'm doing has no relation to login or encryption, so the software included with the reader will probably be useless to me.</p>

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.