Expatriates who are constantly on the move are often faced with the challenge of trying to figure out how expensive life in a new place will be - and whether their new employer has offered a reasonable salary to enjoy a comfortable life.
Gerardo Robledillo, a Spanish software engineer, decided to tackle this issue head on after a series of jobs took him in quick succession from Madrid to Frankfurt to Barcelona and then Prague.
He set up Expatistan.com, a cost of living website that covers five main areas of expenditure: accommodation, food, transport, clothes, personal care and entertainment. Contributors add data from around the world.
"In four years, we've got data for 1,371 cities," Mr Robledillo said.
He assesses the data's reliability on a number of factors including how much there is, how recent it is and how uniform it is. He considers that the data for 114 cities is "fully reliable".
Using the site to compare Abu Dhabi and Dubai, it shows that overall it is 1 per cent cheaper to live in the UAE capital. Food is 9 per cent cheaper, clothes 10 per cent, personal care 13 per cent and entertainment 6 per cent. Housing, though, is a whopping 26 per cent more costly in Abu Dhabi than in Dubai, his data shows.
Each of the five categories is subdivided into specific items - for example in the housing category, a month's rent for a furnished 85 square metre apartment in an expensive part of town, the hourly rate for a cleaner and the monthly rate for an internet connection.
Expatistan.com put monthly rental in Abu Dhabi at Dh9,583 (US$2,608) and in Dubai at Dh7,063.
In July, Barclays approached Mr Robledillo and offered to sponsor the site. "It's a project I work on at weekends and night so it was nice to get something," he said. "They liked the concept and it was good validation that such a big organisation felt it had good value."
Two years ago, Mr Robledillo attempted to add job listings to the site. This was temporarily shelved but he hopes to revive it next year.
Meanwhile he is working on combining the data from Expatistan.com with official data from the World Bank and the European Union to make more sophisticated reports that he hopes to sell for about €50 (Dh243) each.