I'll vouch for BitWarden. You can self-host or use their cloud offering. The server software and all of the clients are open source. I've personally been using

I'll vouch for BitWarden. You can self-host or use their cloud offering. The server software and all of the clients are open source. I've personally been using the cloud offering for several years now and feel quite satisfied with it. The free tier is generous, the premium tier is very affordable, and I can export my data to a self-hosted instance anytime I like.