Most rental buildings in Hanoi that deal directly with prospective tenants do not require going through a broker, which makes their rental listings "no-fee". That being the typical arrangement, variations abound: Some building managers prefer to "outsource" part or the entirety of the rental application process to a brokerage; broker fees may (or may not) be involved under such arrangements.
When this information is available, each building's page will show the rental manager's direct contact information. No-fee rental availabilities are shown directly on each building's page, while brokered "fee" listings are on a separate, linked page. Almost all buildings listed offer unfurnished apartments for long-term lease (typically, 12 or 24 months).