Bitwarden is a free application that will allow you to manage your passwords safely. It is indeed recommended to use different complex passwords for each online service you use.
How to remember all these passwords?
Bitwarden works like a safe, allowing you to store your logins and passwords in a secure way. You will only need to remember one master password to access them.
Automatically generate passwords
The application features a complex password generator and can help you automatically fill in login forms on the sites you visit.
Synchronize your password list between all your devices
You can synchronize your password vault between multiple devices, but also access it from your computer or via a simple web browser. You can also share them with a person of your choice.
Bitwarden in free version
The free version is not limited in number of passwords. The paid version will bring some extra comfort like the automatic generation of TOTP codes (otherwise you can use the free app Authy).