The Campaign Finance Institute (CFI) is a now-defunct nonprofit organization that houses research regarding campaign finance and money in politics. The organization was founded in 1999 and merged with the National Institute on Money in State Politics (NIMSP) in 2018. In 2021, the NIMSP merged with the Center for Responsive Politics (CRP) and began operation as a nonprofit called Open Secrets, the long-time name of CRP’s flagship website.
During its existence as an independent nonprofit organization, the Campaign Finance Institute was funded by many or the nation’s largest left-of-center grantmaking foundations including the William and Flora Hewlett Foundation and the John D. and Catherine T. MacArthur Foundation. The group was also a partner of the left-of-center Democracy Fund, a grantmaker associated with eBay founder Pierre Omidyar.     
The Campaign Finance Institute (CFI) was founded in 1999 and was initially housed at George Washington University in Washington, D.C. In 2000, the group was formally launched as an independent nonprofit. The group’s work mostly centered on collecting research around money in politics and campaign finance laws. The CFI operated a database of state and federal campaign finance laws as they stood every two years from 1996 to 2020. Other resources created by the organization include the CFI Guide to Money in Federal Elections, analyses on small donors and public financing, along with hundreds of other reports regarding money in politics. All reports published by the CFI are archived on its website, which was archived by the University of Albany in 2021. 
Prior to it being folded into the Center for Responsive Politics, the Campaign Finance Institute was led by Michael Malbin as its executive director. Malbin is a professor of political science at the University of Albany who works in a variety of academic and legislative roles in Washington, D.C. He worked as a reporter for National Journal, as a resident fellow at the American Enterprise Institute, and as a guest scholar at the Brookings Institution, and released his early publications around presidential nomination and congressional reform before beginning to focus on money in politics. Malbin led the CFI from 1999 from 2020 and directed its work regarding small donor participation, public financing of elections, and interest groups. Malbin was also a presidential appointee to the National Humanities Council and has been a visiting professor at Yale University. 
Before its 2018 merger with the National Institute on Money in State Politics, the Campaign Finance Institute received funding as an independent organization from many of the largest left-of-center donors and foundations. The group received $450,000 between 2012 and 2016 from the John D. and Catherine T. MacArthur Foundation and $200,000 in 2014 from the William and Flora Hewlett Foundation, both to fund “democracy” related projects.   The group is also listed as a partner of the Democracy Fund, a left-leaning funding arm of Pierre Omidyar’s Omidyar Network. 
Other listed donors to the Campaign Finance Institute include the Carnegie Corporation of New York, the James Irvine Foundation, the Joyce Foundation, the Open Society Institute, the Pew Charitable Trusts, the Rockefeller Brothers Fund, the Smith Richardson Foundation, and the Jennifer and Jonathan Allan Soros Foundation. 
The Campaign Finance Institute was an independent organization from 2000 to 2018. In 2018 the group became a division of the National Institute on Money in State Politics and continued to operate as the CFI. In 2021 it as announced the Center for Responsive Politics, which operates opensecrets.org, would absorb the NIMSP and that the combined would be known as OpenSecrets. Funding to support the merger was provided by the Hewlett Foundation.