It rather depends where you are, but if the project is in NW Europe, I recommend the tools developed by the OPAL project (https://www.imperial.ac.uk/opal/). While the project itself is, I think, over (I'd be delighted if I am wrong on this), the tools are free and are both easy to use and remarkably powerful at measuring biodiversity (https://www.sciencedirect.com/science/article/pii/S1470160X18308252). One of the big pluses is that you can get local volunteers and even school children to help out. We intend to produce versions of the freshwater pack in northern European languages (Polish, German, Dutch and potentially Czech) for a project we're working on and will make these freely available once we have field-tested them.