If you live in the U.S., you probably emit around 19 tons of CO2 in a year, more or less, depending on factors like how often you drive or fly or whether you eat meat. You might have considered offsetting that footprint by supporting projects that shrink emissions somewhere else in the world—but you might also have read stories about problems in some past projects where trees weren’t actually planted or were later cut down . A new carbon offset startup focuses on transparency, showing customers photos, satellite images, and other data to prove how their money is helping.

“What we kept hearing was, ‘Where does my money actually go? What’s happening here, and how do I know they’re really planting as many trees as they say they will, for instance?'” says Landon Brand, one of the three cofounders of Wren, the new startup, which is one of the companies in Y Combinator’s current cohort. “There’s a lot of potential for fraud in the space. Our initial inspiration was seeing that skepticism that comes from not knowing what happens with your donation.”

The company starts by leading you through a well-designed carbon calculator that pulls up the average carbon footprint for people living in your country and then asks a few key questions, such as whether you drive and the size of your home. To get a more detailed footprint, you can answer more questions, from the size of your electricity bill to how much you spend on clothing each month. With your total footprint in hand, you can buy a monthly subscription to offset all of it. (For many people, offsetting their entire carbon footprint through the platform could cost around $15 a month.)

Wren sends money to projects like a program in Peru that works with indigenous community members using drones and satellite data to spot early warning signs of deforestation; each month, people buying offsets to support the project get updated on any activity and patrols that happened to protect the trees. In East Africa, users support a project that trains farmers to plant trees and then pays them to maintain the trees as they grow. Updates include satellite images showing where specific trees were planted and data about the size of each tree as it grows. In some cases, the startup is working with nonprofits to help make data they’re already collecting easier for people buying offsets to quickly understand.

Each project has a meaningful impact. The startup wanted to help give people who were focused on issues like plastic straws a way to act at a larger scale. But, of course, offsets aren’t a full solution. Wren plans to later use its site to help direct people to more systemic solutions, such as signing petitions in support of a carbon tax that would push corporations to move more quickly to cut emissions across the economy. It also hopes to help nudge users to shrink their footprints, not simply rely on carbon offsets. But the offsets are a place to start. “Wren is something that they can do today to have a positive impact on the environment,” Brand says.