Some years ago Christian Kofi Adu Vanlare wanted to buy a “really big birthday cake” for his uncle, the family patriarch, who was turning 88. But there was a problem. Mr Vanlare lives in New Jersey on America’s east coast. His uncle lives in Accra, Ghana’s capital. Icing and sponge do not travel well, and simple things like organising a cake can be onerous in a bustling African city. Various cousins said they were too busy to procure a gateau.

Eventually he had a slice of luck when a friend relented and went to the shops. The big uncle got his big cake. But making a meal out of buying a dessert was a reminder of the challenges of being abroad while having commitments back home. “For those of us who live in the diaspora this is our daily problem,” says Mr Vanlare.

So he came up with a solution. Somafour (“One who is sent” in Akan, a language spoken by most Ghanaians) is an app that connects Ghanaians in the diaspora with those in Ghana who can run errands on their behalf. Mr Vanlare’s startup is unlikely to attract the attention of venture capitalists in the near future. But its very existence reflects the growing number of Africans living overseas and their economic importance to the continent. It also offers a lesson in the role of trust in getting things done.

Africans account for a fraction of immigrants in most rich countries but their numbers are rising. More than 2m immigrants from sub-Saharan Africa lived in America as of 2019, a 16-fold increase since 1980, according to the Migration Policy Institute, a think tank. By one estimate in 2022, there were roughly 500,000 Ghanaians living in OECD countries.

That is a fraction of the 34m in Ghana itself, but their money matters. In 2023 the $4.6bn in remittances to Ghana was more than the country received in aid and FDI combined. In addition, hard currency goes a lot further these days. The Ghanaian cedi has lost about two-thirds of its value against the US dollar in the past five years. This has encouraged some in the diaspora to buy land while their dollars are worth more. One Somafour agent says he was asked to visit the land a customer had bought to check the quality of the plot. Dealing with bureaucrats at the land register office can also be part of the job.

Other errands can be more personal, such as taking elderly relatives to the doctor or delivering drinking water to clients’ parents. Another agent recalls the funerals she has attended on behalf of friends of the deceased. She delivers donations to the bereaved families. (These may help with the cost of custom coffins that are popular in the west African country. Ghanaians have been known to be buried in coffins shaped as cars, cocoa pods and fish.)

Mr Vanlare admits, however, that business has been slow so far. Many Ghanaians are wary of using an app rather than asking family for help, even if their kin are unreliable. In a global survey of values, albeit from a decade ago, just 5% of Ghanaians agreed with the statement “most people can be trusted”, a standard result for a poor country. “In the African context it is very difficult to break into family networks,” says Mr Vanlare. It is not a piece of cake.