Intern's day-to-day responsibilities include: 1. Key Responsibilities: Develop, test, and maintain web applications and backend services. 2. Collaborate with senior developers to design scalable and efficient solutions. 3. Write clean, maintainable, and efficient code. 4. Build and integrate RESTful APIs. 5. Work with databases and optimize queries. 6. Use Puppeteer for web scraping, automation, or testing tasks. 7. Troubleshoot, debug, and upgrade existing systems. 8. Participate in code reviews and team discussions.