Most SIPs lock a date and never check it. This looks at a fund’s published NAV history, runs a monthly SIP on every day from the 1st to the 28th, and names the one with the highest XIRR. If the spread is tiny, it says noise, that’s a real answer, not a failed lookup. Free, no account, Indian mutual funds only. Not advice. Try a fund you already own and comment what felt unclear or wrong.