Free checking accounts are on the wane at traditional banks, according to a survey released Monday. But customers can still avoid monthly maintenance fees at a majority of online banks.

Just 31% of the 100 U.S. banks surveyed offered free checking accounts, compared to 35% a year before. No-fee accounts were even rarer at brick-and-mortar banks. Just 28% offered checking accounts without monthly fees.

Online banks bucked the overall trend, with nearly 79% offering free checking accounts. Online companies that did require monthly fees charged an average of $9.49, compared to $12.48 at traditional banks.

Overdraft fees were also lower at online financial companies, hovering at $25.50. The average overdraft cost at brick-and-mortar banks was $31.90.

MoneyRate's semi-annual report surveys the 50 largest U.S. retail banks by deposits, as well as 50 smaller financial companies.