The Institute of Fundraising is holding an interactive seminar next week to work towards a web site allowing users to compare charities' performance.
The project is going ahead despite a Treasury grant to Guidestar UK, the new internet service sponsored by the Charity Commission, which will also provide information about charity performance.
The Institute of Fundraising insists that the two sites are not rivals.
"Our site will focus on donors, while Guidestar will be used by the Government, academics, trusts and foundations," said Simon Hebditch, director of policy at Charities Aid Foundation, which is involved with the project.
The news follows concerns about the long-term financial viability of Guidestar UK.
However, Guidestar is confident that it can raise the £550,000 a year needed to satisfy the conditions of the Treasury's grant.