Bernie Sanders popularized crowdfunding in politics by raising $220 million in small donations. An example of the challenges with handling a high volume of donations is the 2016 New Hampshire primary night, when Sanders asked a national TV audience to donate $27. Traffic peaked at 300K requests/min and 42 credit card transactions/sec. ActBlue is the company behind the service used not only by Sanders, but also 16,600 other political organizations and charities for the past 12 years. This presentation is about the lessons we learned building a high performance fundraising platform in Rails.