https://www.passbolt.com/pricing/pro
https://www.passbolt.com/vs/bitwarden/overview
https://www.passbolt.com/docs/hosting/install/
PHP backend (IMHO a downside): https://github.com/passbolt/passbolt_api. But There appears to be a significant amount of auditing behind Passbolt's security claims, assuming the information on https://www.passbolt.com/security is accurate.