By Dave Sharp ( and Piyush Tantia, a technology-driven nonprofit and online fundraising platform, is dedicated to creating an easier and more meaningful giving process for both donors and nonprofits. As is the case for many platforms, maintaining operational sustainability while offering free services to other nonprofits poses a significant challenge. A key component of their sustainability model involves encouraging donors to add a voluntary “tip” when making donations, which helps cover the costs of maintaining the platform. However, over the first year of including this feature, they found that only 30% of donors were adding this tip. 

To help bump this up and meet more of their operational costs, partnered with ideas42 to develop new concepts for the tipping experience. uses a sliding scale for tipping. Donors can adjust their tip from 0% to 30% of their donation, with the default set at 15%. A short message above the slider explains that is a nonprofit, and that making this additional donation helps keep the platform free.

Sliding scale suggesting a 30% "tip" to the platform hosting a digital donation transaction.

The team’s hypothesis was that loss aversion could be a reason for low tipping. Nobel laureates Daniel Kahneman and Amos Tversky found that people evaluate losses and gains relative to a reference point that is often set by something in the present situation. In the case of tipping, the donor’s reference point would be set to the amount they chose to donate ($20 in the example above). Then the next screen asks for a tip, which could feel like a loss against their reference point of $20 because they hadn’t planned to spend any more. 

Another possibility was that donors did not believe that most people tip a giving platform. In psychology terms, their perception of the social norm was that tipping is not customary. Social norms can have a strong influence on behavior, and come in two flavors—injunctive and descriptive. The former is what we believe to be the expected behavior and the latter is what we perceive other people doing. In this case, donors possibly believed that tipping wasn’t expected and they also couldn’t see what others were doing.

Building on these psychology insights, the team came up with three concepts they were interested in exploring further.

  1. Suggested donation: We considered changing the header from “Add a donation to” to the familiar “Suggested small donation to” Using the word “suggested” conveys an injunctive social norm that tipping is customary.
  2. Constrained choices conveying a norm: Replacing the slider with just 3 options for a tip percentage, just like some restaurant receipts and retail checkouts now include, could signal to donors that tipping is expected.
  3. Responsive messaging: Psychology research on choice suggests that telling people the consequences of their choices has an influence on their decision. We wanted people to tip because they understood why it was impactful and they felt good about doing it, and we wanted them to understand the negative consequences of not leaving a tip. However, getting people to read text in any user interface is a big challenge. So how could we get users to read a short message that explained this? Things that appear or disappear as a result of user actions get registered as “important.” We considered creating a message that would appear or disappear depending on whether or not the donor was including a tip.

After some quick prototyping of the concepts above, we decided that having the interface change in response to their tip choice was the most promising. First we thought about a message that would show up if they moved the slider down to $0. It would say something that would make the impact of not tipping clear—other donors will need to cover the cost of the platform in order to keep it free for nonprofits. However, we didn’t like that explaining these consequences felt like shaming donors into supporting We wanted donors to tip because it made them feel good—they were supporting a nonprofit that was helping their chosen nonprofit raise money. A negative message might increase tipping, but it could leave donors with a lingering discomfort rather than feeling connected or fulfilled.

So we decided to flip things around. A message would show whenever the tip amount was greater than $0. It would thank donors for supporting and keeping the platform free for nonprofits. Inspired by a social norms sticker with a smiling water droplet that ideas42 designed to encourage water conservation, we thought the addition of a green thumbs up icon next to the message might also help convey a social norm. Importantly, if they moved the slider down to $0 the message would disappear, and the slider would go from green to greyscale.

An animated gif showing how a colorful thank you message disappears when the sliding tip scale is moved to zero.

This design emphasized the good feeling from supporting with a tip. If donors decided not to tip, the visual cues for that good feeling would go away. Choosing not to tip might not feel as good, but it would never feel bad.

We launched a test of this responsive messaging at the end of 2023. There were three variations of the thank you message with our current design as the control.

  • “Your added donation is keeping this fundraising platform free for every nonprofit.”
  • “Thank you for empowering nonprofits and inspiring generosity by adding a donation for!”
  • “Thank you for keeping this fundraising platform free for every nonprofit.”

All three performed better than the control, but the shortest thank you message did the best. It increased the donor tip rate from 44% to 59% (a relative increase of 34%). There was an additional and unexpected result as well. It also increased the chance of guest donors creating an account by 62%, and increased the chance of a donor making a second donation on the platform by 61%. Most of these second donations happened within a few minutes. So the added tipping message not only meant more support for, but also more support for the other nonprofits on our platform.

With any ask for an additional donation there is always a risk that donors feel pressured and therefore have a worse experience. However, donors’ increased engagement with suggests that donors’ experience was improved from the tipping “nudge” rather than being harmed. It was a big win all around. Donors were more satisfied, was receiving more operational support, and more nonprofits were receiving donations.