I got frustrated with existing Indian finance calculators.
They're slow, cluttered, require logins, and most don't
understand Indian-specific products like step-up SIPs,
floating rate EMI tracking, or the old vs new tax regime.

So I spent a few weeks building one from scratch.

What it does

• Home Loan EMI with full month-by-month amortisation table
• Prepayment tracking — add a lump sum on any month and see exact interest saved
• SIP, Step-up SIP and Lumpsum projections
• FD & RD maturity calculator
• Old vs New Tax Regime side-by-side comparison
• Goal-based SIP planner with inflation adjustment
• SWP (Systematic Withdrawal Plan) calculator
• Multi-loan EMI comparison with Best Value highlighting

Tech used

• Pure vanilla JS — no React, no Vue, no build tools
• Chart.js for all visualisations
• Single HTML file — entire app is one file
• Hosted free on Netlify
• Mobile responsive with CSS Grid and Flexbox

Interesting challenges

Step-up SIP calculation was trickier than expected —
you can't use the standard SIP formula, you have to loop
month by month and increment the contribution every 12 months.

Prepayment tracking required rebuilding the entire
amortisation schedule dynamically on every input change,
recalculating every future month's opening balance.

Old vs New tax regime — the slab structures are
completely different so I wrote two separate tax functions
and run both on every calculation.

Live tool

👉 https://smartfoliotools.netlify.app

Completely free, no login, works on mobile.
Would love feedback from the community — especially
if anything looks wrong on your device!

What's next

Planning to add:

• NPS calculator
• HRA exemption calculator
• Capital gains tax calculator

Any other Indian finance tools you wish existed?