Chitragupt

The problem

Every Indian tax calculator answers one question — which regime is cheaper for you, one person, this year. That is the wrong unit. Tax in an Indian household moves across people: a parent's medical premium, a spouse's home-loan interest, a child's tuition. Filed one at a time, a family routinely leaves a deduction on the table that was always claimable.

What it does

• Parses a Form 16 upload into a structured return, rather than asking you to retype it.
• Shows both regimes side by side with the delta stated in rupees, not drawn as a chart.
• Adds a household lens across spouse, parents and kids, surfacing deductions that only exist between people.
• Runs a 15-question Quick Check for anyone without a Form 16 to hand.
• Prints what you can act on the refund claimable and the deductions still unused.

Decisions worth defending

• Zod as the only contract. Tax rules change every budget. A schema shared by the form, the function and the stored document means a rule change is one edit with the type system finding the rest. No hand-written DTOs on either side.
• 189 small functions, not one service. Each deduction is its own function with its own tests. Wrong numbers are the only failure mode that matters here, and this shape makes a wrong number traceable to one file.
• The verdict is free. Which regime wins, and by how much, costs nothing. A tax tool that computes a number and then asks for money before showing it has already lost the user. The paid tiers are the full workings and the household lens.