Custom HTML Form Developer Required

Project Overview:
Please strictly adhere to the budget stated in the bid. The offer cannot be modified afterwards.
I’m looking for a developer to build a custom HTML form that will present approximately 400 questions of various types: Yes/No, image-based, and short text answers.
The questions currently exist in Google Forms, and the responses are already being stored in a Google Sheets document.

This new HTML-based form must:

Submit responses directly to Google Sheets using a Google Apps Script Web App.

Allow each user to access the form via a unique, single-use link tied to their email address (login required).

Include a countdown timer (e.g., 20 minutes total) for the entire session.

Be optimized for a clean, responsive, and distraction-free experience.

Key Requirements:

Develop a custom HTML form with ~400 questions (Yes/No, images, short answers).

Use appropriate input types: checkboxes, image fields, and text inputs.

Save all responses to Google Sheets via Google Apps Script.

Implement unique link access per user (one-time email login required).

Include a global countdown timer for the entire form (e.g., 20 minutes).

Ensure simple, modern, and mobile-friendly UI/UX.

Ideal Developer Profile:

Proficient in HTML, CSS, and JavaScript.

Experienced with Google Apps Script and Google Sheets integrations.

Knows how to implement secure email-based access control and session limits.

Familiar with timed forms and managing large question sets efficiently.

Strong eye for usability and clean design.