The Charity Commission has made the accounts of 35,000 charities available on its website, as recommended in the Government's 2002 Strategy Unit Report.
Charities can now register and submit annual accounts electronically, but commission records are also being transferred to computer, replacing 700,000 paper files.
Nick Allaway, the commission's director responsible for improving charity information, said the changes will improve public faith in the sector.
"Charities get certain fiscal benefits, so it's important the public sees where its money goes," he said.
Under the changes, charities with annual incomes exceeding £1m will also give detailed information about their activities. "One of the criticisms we've had is that we provide only financial information," said Allaway.
"This gives the public more of a feel for what charities are doing."
Accounts not yet on the website can be obtained from individual charities' trustees or the commission's contact centre.