About Poptani Labs

Poptani Labs is a tiny workshop for free web tools — currently home to one project: a free, open Systematic Withdrawal Plan (SWP) simulator for Indian mutual funds (see it live at poptanilabs.com/swp). It replays history using actual daily NAVs: you choose a scheme, a lumpsum investment and a withdrawal plan, and it shows exactly how the corpus would have evolved — withdrawal by withdrawal — including the remaining value and the XIRR of the full cashflow.

Where the data comes from

Scheme lists and NAV histories come from mfapi.in, a free community API for Indian mutual fund NAVs. The scheme list refreshes daily; each scheme's full NAV history is fetched on demand when you select it.

How the math works

Your lumpsum buys units at the NAV prevailing on (or nearest before) your investment date.
Each scheduled withdrawal redeems units at that date's NAV. If a withdrawal exceeds the balance, the plan pays out the remainder and ends.
Remaining value is marked at the latest available NAV; XIRR is computed over the full cashflow (lumpsum out, withdrawals in) with Newton's method.

Who is behind it

Built by Pawan Poptani as an open learning project — first as a Python/Streamlit app, now as a fast static website. The original code lives on GitHub.

Disclaimer: Educational tool only — not financial advice. Mutual fund investments are subject to market risks; read all scheme documents carefully.