FilaMan is a fully open-source (MIT), self-hosted filament manager built around a DIY ESP32 scale and PN532 NFC, with a large open community database and printer hooks for Bambu, Klipper and OctoPrint. It's a great fit if you want to own your whole stack, run your own Docker server and enjoy building hardware, and it's free to self-host (its mobile apps put core features behind a paid in-app purchase).
SimplyPrint is a connected filament manager that's been running inside a print platform since 2020: it reads the G-code of every print on any connected printer, including cloud Bambu and Prusa, and deducts filament automatically, with no scale, no broker, no plugin and no server to run. Add native cross-brand NFC and AMS auto-import from your phone or browser, direct Dymo and Zebra label printing, free iOS and Android apps, the open MIT Open Filament Database (143 brands), and a full platform around it, all free on every plan. If you want tracking that just happens with nothing to build, that's SimplyPrint; if self-hosting an open-source tool and building your own scale is the point, that's FilaMan.