Future Me - Send an email to your future self
Notopass - Share your accounts without giving username/password
Letter to Yourself - Send a physical letter to your future self
1Password - 1Password can create strong, unique passwords for you, remember them, and restore them, all directly in your web browser.
Letter to my future self - Letter to my future self is a prominent email scheduling service that gives you the opportunity to create a letter with goals and thoughts for your future self and schedule a date for sending it.
SuperTokens - Open Source User Authentication - An Alternative to Auth0 / Firebase Auth / AWS Cognito