Saas: Rate Calculator & Engangement Calculator for Influencers

I’m building a simple, web-based SaaS tool for social media influencers. It needs two core features:

Rate Calculator (we can go into more detail when accepted):
•⁠ ⁠Inputs: follower count, average reach/engagement rate, platform (Instagram, TikTok, etc.) - we have the data for the range of pricings
•⁠ ⁠Outputs: suggested price per post/story/video (this will come as a range) and potential ROI (based on our engagement rate calculator)

Engagement Calculator (we can go into more detail when accepted):
•⁠ ⁠Inputs: Influencers @ which will pull in their open source information on the IG API.
•⁠ ⁠Outputs: engagement rate % for the last 10 paid posts and 10 organic posts (per following, per reach, per impression, per engagement)

Key Requirements:
•⁠ ⁠Responsive user interface (desktop + mobile)
•⁠ ⁠User authentication (signup/login) and dashboard to save past calculations
•⁠ ⁠Clean, easy-to-read results (tables or simple charts)
•⁠ ⁠Well-documented code and deployment instructions

Who You Are:
•⁠ ⁠A full-stack developer comfortable with React (or Vue) and Node.js (or Python/Ruby)
•⁠ ⁠Experienced in building calculation tools and user dashboards
•⁠ ⁠Detail-oriented, communicates clearly, and meets deadlines

Please include in your proposal:
•⁠ ⁠Brief outline of your approach
•⁠ ⁠Examples of similar projects you’ve done
•⁠ ⁠Estimated timeline and cost

Looking forward to working with someone who can deliver a reliable, maintainable tool.