Ryan Kelly developed the software to automatically refresh websites such as eBay, but told Channel Four News he had received emails from Iranians saying they were using it to bombard official websites with hits, making them crash.
The 25-year-old from London said the number of visitors to the site where the programme is available, www.pagereboot.com, has surged in recent days.
"Later I got lots of emails from Iranians saying they were using the application to attack government websites and bring them down," he said.
Iran's capital Tehran has been rocked by protests for four days since the results of Friday's presidential election were announced, amid complaints of rigging from supporters of Ahmedinejad's main challenger, Mir Hossein Mousavi
Kelly had to take his website down because the huge spike in Internet traffic was exceeding his server limits. But after an online appeal for donations to cover the increased costs, he was able to make it available again.
"I agree with what they are doing and will keep it up there as long as I can, and as long as the server does not overload," he told Channel Four News.
The Internet has played a crucial role in the Iranian election, with reformists using it to mobilise supporters and circumvent their lack of access to state-controlled media in the run up to the vote.
