'No-cost' doesn't mean 'free'
In a true no-cost refinance, a lender credit built into a slightly higher rate covers the closing costs so you don't pay them out of pocket. The costs still exist, they're just being paid a different way. Understanding that trade-off is the whole game.
When it may make sense
It can make sense when rates have moved meaningfully in your favor and you don't plan to hold the new loan for many years, or when preserving cash matters more than shaving the last fraction off the rate. Whether it pencils out depends on your current loan, expected time in the home, and market conditions.
How to spot marketing dressed up as strategy
If someone quotes 'no-cost' without showing you the rate difference versus paying costs, the credit amount, and the break-even, you're being sold, not advised. A real analysis compares both paths in dollars and time.