Visa information for Bangladesh differs between websites.
In general you can get a visa on arrival or you can enter without a visa.
Passport holders from Afghanistan, Algeria, Brazil, Egypt, Hong Kong, India, Iran, Iraq, Jordan, Kenya, Lebanon, Libya, Mauritius, Mexico, Morocco, Myanmar, Nigeria, Pakistan, Philippines, Somalia, South Africa, Sri Lanka, Syria, Thailand, Uzbekistan, Vietnam and Yemen.
This list changes frequently so please check before you make plans. Note: Bangladeshi nationals holding dual citizens need not have a visa provided their passport is stamped with "No Visa Required". Visas are available on arrival for some nationalities for a US$50 fee. It may be cheaper to get a visa on arrival than to buy one at a consulate.
Officially if you are from a country without a Bangladesh embassy, you can get one at the border/airport, but do not rely on it. Please double check.
General information about Bangladesh visas
Bangladesh foreign affairs
Bangladesh Visa on arrival eligibility