Full-Stack Quiz App Development

I'm looking for an experienced full-stack developer to create a quiz-based web application. The quizzes will predominantly be multiple-choice format and should include the following features:

- User Authentication: Secure sign-up and login via email and password.
- Timed Quizzes: Users will have a set time limit to complete each quiz.

Ideal Skills and Experience:
- Proficiency in both front-end and back-end development.
- Experience with implementing secure user authentication.
- Familiarity with timer functionalities in web applications.
- Strong knowledge of databases to manage user data and quiz content.

Please provide samples of similar work done.