A new database allows the public to search a government archive of 41 million wills dating back to 1858.
Wills have always been public documents and the existing Â£10 fee for each document applies to downloads.
A name and year of death is required to find wills, which should be ready for download within 10 days of order.
The archive can be used to trace family history, and to view the wills of famous names including AA Milne and Beatrix Potter.
It contains wills from England and Wales. Different procedures apply in Scotland and Northern Ireland.
The database also includes the wills of those who died while serving in the British armed forces between 1850 and 1986.
BBC correspondent Nick Higham said the scheme would be supported by staff at the Birmingham warehouse where the documents were housed.
"For many wills, someone still has to locate the physical copy in the warehouse, scan it and send it off," he said.
"They've taken on extra staff, but admit that no-one's ever made such a large database of documents available to order online and it's hard to predict demand for the service."
Courts minister Shailesh Vara said: "This fascinating project provides us with insights into the ordinary and extraordinary people who helped shape this country, and the rest of the world."
Millions of wills - including those of Sir Winston Churchill, Alan Turing and Princess Diana - are now available online.