Balaji's advice is solid but I'd push back on one thing — he says don't use the counter-offer as leverage. I actually think you can use it, but the timing and framing matter a lot.
If your current company gives you a written counter-offer, that's real market validation. You can mention it without being aggressive: *"My current employer has also revised their offer, so I want to make a fully informed decision. Can we revisit the number?"* This signals you're not bluffing and you have options. Works better than just citing Glassdoor honestly.
That said — and this is important — only do this if the counter-offer is genuine. Don't fabricate or exaggerate it. HR folks talk, especially in the same industry in a city like Pune, and if you get caught inflating numbers your reputation takes a hit.
The other thing I'd add: target the right person. Sometimes the HR recruiter has a fixed band they cannot move from. Ask to speak with the hiring manager directly for compensation discussion. Hiring managers often have more budget flexibility and they actually want you to join, so they'll fight for you internally in ways a recruiter won't.
Also, if base salary is truly stuck, ask for a joining bonus. Many product companies in India have this as a separate budget. A ₹1-1.5L joining bonus isn't unusual and it doesn't affect their annual comp band.
Bottom line: go in with ₹18L as your ask, have your reasons ready (market data, your skills, competing offer), and don't apologize for negotiating. Confidence is half the battle here.