I need a browser-based finance calculator that lets my team produce accurate rental quotes and early-payout figures without digging through rate charts. How it will be used – Salespeople will enter the equipment cost, contract duration (24, 36, 48 or 60 months), invoice amount, total payable over the term, instalment value and product type. – With one click they should see the monthly instalment, total finance charge and an early-payout figure. – Managers and administrators must also be able to view internal brokerage rates that remain hidden from sales staff. Key functions • Front-end: clean HTML5/JavaScript interface that works on any modern browser so I can simply share a link with the team. • Rates engine: the calculator must pull its figures from a rate table I can update myself (CSV upload or a small admin page is fine—whatever is quickest to maintain). Rates do change, so I need edits to take effect immediately. • Role-based access: three levels—Salespeople, Managers and Administrators—each seeing only the data relevant to them. A lightweight PHP/MySQL login or a JSON-based credentials file is acceptable, as long as setup is straightforward. • Early-termination logic: entering the actual months elapsed should instantly produce the correct payoff amount. • Variations: the tool should handle “what-if” scenarios (e.g., different product types or rate tiers) without reloading the page. Deliverables 1. Responsive HTML/CSS/JavaScript calculator page. 2. Back-end or config file for updating rate tables. 3. Simple authentication layer reflecting the three user roles. 4. Brief setup guide so I can deploy or move the tool without outside help. If you have experience building lightweight finance tools or rate calculators, especially with dynamic tables and role permissions, you’ll hit the ground running here. I’m happy to answer technical questions quickly so we can get this live for the sales team.