Static website is kinda boring...

You don't want the username or password to be empty. It is also better to add checks to the database in addition to checks in the backend.

The database will filter users on its own much faster, and you won’t have to search for the user in the list.

If you want other people to be able to run this project, they must be able to get the database into the required state.

Migrations are often stored as numbered files. A separate table is created in the database to track which files have been applied.

Storing passwords in plain form is not safe. See password storage cheat sheet if you need more information.

Establishing a connection is not the fastest process. For optimal performance, you should maintain a connection pool.

Handle errors and send the appropriate message to the user. Otherwise you will have constant crashes.

For example, during registration you should not require a user ID, because it is generated either by the database or the backend.

When sending user information, it is better not to send even a hashed password to the user.

Also, in the future, the database may store additional parameters that you do not want to transmit to users in any form.

Username, password, host and port must be configured through environment variables or a settings file.

Instead of individual parameters, you can request a connection URL so that users can specify additional parameters.