Alexandrea Mellen developed her first iPhone application during her sophomore year at Boston University. At the time, she was building what she needed. One year and three apps later, she is focused on building what everyone else needs, dedicated to making a difference through engineering.

On April 15, 2013, Mellen accompanied her sister to her first Boston Marathon. The two walked the entire length of the race, strolling by the finish line 15 minutes before the first of two bombs went off, killing three and injuring more than 260 others.

“It was really one of the most horrifying experiences of my life,” Mellen said, reminiscing on the tragic day and the screams of innocent bystanders. “It was a wake-up call for me that everyone’s time is limited. It’s important to help people and do what you can now.”

That summer, Mellen stopped making excuses. Not having enough time, or being in school, weren’t reasons she couldn’t turn her first app into a company.

“I decided I wanted it to be a real company and that I wanted to make a difference,” Mellen said. “And I thought apps could be the way to do that.”

So, she launched Terrapin Computing as the umbrella company to the iOS apps she was developing.

Her first app, called the Resistor Color Coder, was meant to help people decipher resistor color codes, which are used to indicate the values or ratings of electronic components. With the app, users can simply touch the band they want to change and choose the color they need — the app handles the rest.

“It was really more just for me,” Mellen acknowledged, “a tool I wanted to use.”

But, when she started building her second app, Lewis Dot CHEMISTRY, she realized she was developing a tool fellow students could use.

The app features more than 50 Lewis dots, or rather electron dot diagrams, that highlight the bonding between atoms of a molecule, as well as any unbonded electron pairs. Alongside each Lewis dot, Mellen included a fun fact to help students dive deeper into chemistry.

And it worked. She just recently sold 700 copies of the app to one school at 99 cents a download, and has a few similar apps lined up scheduled to be released “shortly.”

In the meantime, Mellen has also designed a travel app, dubbed TripPic, that lets users add the time, date, location and a custom message to photos as they’re being snapped. For those on road trips, photos can be captioned directly. Or, according to Mellen, food critics can better keep track of the name of their new favorite restaurants by dropping a note directly on to their Instagram-ready meal.

“Most of my apps have thus far filled a need,” Mellen said. “What I would need or what I think students would need.”

She has plenty of access to students, after all, given Mellen is also a partner for Dorm Room Fund Boston, a student-run venture arm of First Round Capital.

Mellen got involved in schools beyond Boston University the summer before she started attending. She served as an undergraduate research assistant at MIT, working with Group Sadoway on researching liquid metal batteries for grid scale energy storage. At Boston University, however, Mellen has become a member of the BU Entrepreneurship Club, as well as an educational instructor for the Global App Initiative at BU, whose mission is “to teach students the skills necessary to develop mobile apps for nonprofits.”

“I sat down with the people who ran [Dorm Room Fund Boston] last year, and they were just amazing people,” Mellen shared. “They were so involved in their personal college communities. It’s amazing to see what they accomplished.”

The same could be said for Mellen, though.

After she graduates from Boston University in the spring, she plans to take a year off and focus on Terrapin Computing. During that time, she’ll be maintaining the current apps she has, all while potentially building a game. Her next move will likely be based around hearing what other people need.

She was inspired by First Round Venture Partner Wiley Cerilli in that way. Mellen recently met Cerilli, the founder of business listings startup SinglePlatform, which was acquired by Constant Contact in 2012, and recalled a point he made during a conversation with Dorm Room Fund student investors.

“When he was trying to figure out what to make, he just went around, talked to people and asked, ‘What would make your life easier?'” Mellen shared. “There are so many people who sit there and say, ‘Oh, I don’t know what I want to do.'”

Not Mellen, though.

“That’s something I’ve been looking to do myself,” she said, referencing Cerilli’s founding story.

So, what would make your life easier? The idea could turn into Mellen’s next app.

Images via Alexandrea Mellen