Numbeo

Numbeo is a Serbian crowd-sourced online database of perceived consumer prices, real property prices, and quality of life metrics. The website was founded in April 2009 by former Google employee Mladen Adamović, to enable users to share and compare information about the cost of living between countries and cities. Since 2012, the website has been operated by NUMBEO DOO Beograd-Palilula, a Serbian private limited company run by Adamović. According to Adamović, the website earns money through advertising and the sale of subscriptions to its API.

Numbeo's crowd-sourced data can be inserted or altered by anyone accessing the website, and is not peer-reviewed. Data is also manually gathered by the operator, from sources such as company and governmental websites, which is done in half-year intervals; it is then combined with user-generated data by giving it extra weight in the final score calculation, according to the company. As of 2017, it was the largest database of user generated data about cities in the world. As of 2020, this possibly applied to (user generated) data on housing prices as well. The quality of life index is a combination of eight sub-indexes: purchasing power, safety, healthcare, cost of living, property price to income ratio, traffic commute time, pollution, and climate.