Yeah, I asked @RebeccaTrevalyan from LibraryofThings.co.uk about this and she said:
Software- most LoTs/ Tool libraries use MyTurn (http://myturn.com) It’s not open source and the UX is a bit clunky sadly - but does the job for testing.
We’ve ended up building our own software (Library of Things) because the self-serve kiosk model we developed couldn’t be supported by MyTurn. It’s also not open source (not psyched about Amazon/ Bosch etc ripping it off), but v open to licensing it to the right folks.
I’ve also recently discovered Snipe-IT which is a powerful open source web designed for IT asset management, but I don’t see why it couldn’t be used for any other type of assets too. Think it could well work well for a Library of Things (that’s kinda sorta what asset management stuff is - think checking out laptops, projects etc at Universities etc):