If you are an expatriate in Hanoi city, Vietnam, If you are looking for a house to rent, please know that real estate agents do not charge any commission for Renters, all agent fee is being paid by landlords.
So, if you will ever deal with any real estate agent / broker who ask for commission, please avoid them at any cost.

https://vietlonghousing.com is a reputable real estate site which have largest property listings for rent in Hanoi city.