With hundreds of millions of monthly active users around the globe, Pinterest is one of the world’s most-loved apps. A look under the hood reveals unique technical challenges — from advancing visual search, to handling the diverse needs of international users, to recommending the right Pin to the right person at the right time. Here, Leah Bueing (Ad Measurement Software Engineer), Sha Sha Chu (Android Tech Lead), Wendy Lu (Ad Formats Engineering Manager), and Justin Mejorada-Pier (Analytics Platform Tech Lead) share what drew them to the team, describe the technical problems they’re solving, and explain what makes Pinterest’s culture unique. Interested in learning more? Check out Pinterest’s Engineering blog and open roles, or get in touch!
What’s your role at Pinterest, and why did you join the team?
Justin: I’m the technical lead on the Analytics Platform team, which builds the data products and apps other Pinterest engineers use for things like managing A/B experiments, keeping track of metrics, and querying datasets. I joined in 2014, but I remember reading about Pinterest and checking out the site a couple of years before that. It stuck with me, because I’d never seen a UI like that — I thought it was really interesting, visually and technically. So when an opportunity came up, I already knew I liked the product.
Then I started thinking about the potential machine learning would have on a product where one of its core assets is human-labeled data, where every Pin is a new categorization. I also watched a couple of videos from the founders, and they seemed like very grounded people. I felt like I could trust them to do the right thing in terms of building a company that would have a positive impact on people’s lives.
Finally, I looked through the app reviews in the iTunes store, and I was sold. Users weren’t saying, “I really like Pinterest.” They were instead saying how much they loved it.
“Users weren’t saying, ‘I really like Pinterest.’ They were instead saying how much they love it.” — Justin
Wendy: I’m an engineering manager on the Ad Formats team. We handle new formats and features for Pinterest’s ad clients, and own how Pinners interact with and take action on ads. I joined in early 2013, when the company was only about 90 people. My friends and I were all on Pinterest, and I wanted to work on a product that I used every day, because I felt like I could make a bigger impact if I identified with the users.
I also thought the team was great. We just sort of clicked when I interviewed, and I could see myself working here. And like Justin, I really liked the idea of working on a product users loved so much. People were sending in poems and love letters about Pinterest — which we still have up on a wall in our original building.
Sha Sha: I’m the tech lead for the Android Platform team, which means I’m responsible for the overall technical direction of Android development here. I worked in gaming before I joined Pinterest, first at a AAA company, then in mobile games, then on a streaming games platform. Each role took me further from actually making games, which was what got me into CS in the first place. But that helped me realize I cared as much about the people I worked with and the types of problems I was solving as the product I was building.
Then an opportunity to join the team here came up. I knew Pinterest had a really nice Android app, and the company was also at a good size for me. My wife and I were about to have a kid and I was looking for more stability, but I didn’t want to be one of 60,000 people. Pinterest had an established product, but still a lot of interesting work to do.
Leah: I work on the Ads Measurement team, on third-party integrations and internal tooling. Pinterest is actually my first industry job. Before I worked in tech, I used to be a teacher and then attended Ada Developers Academy a few years ago. I used the app all the time for school and cooking, and I loved it. So when I heard they were looking for a junior developer, I was like, “No way! I could work for Pinterest?”
The other big factor for me was the team culture here in Seattle, where I work. People took time to meet with me outside my interview, and I felt so welcome. It seemed like an incredible place to grow and learn, and I could tell I’d have a lot of support.
What kinds of technical challenges are you facing?
Sha Sha: A major challenge here is the scale. We’re very lucky to work on a product hundreds of millions of people use, but that does mean everything is amplified — good and bad. For mobile, that includes making the app perform well in new international markets, where network speeds are slower and people may not have the latest and greatest devices.
There was also a time at Pinterest where the goal was to get things done as quickly as possible. Now we’re focused on building software that will be going strong 10 years from now, and there’s a lot of work to do. But I think that creates an opportunity for everyone, because that work is everyone’s responsibility. If you discover an issue, it doesn’t matter whether it’s technically within your area. You should always leave the code better than you found it.
“We’re focused on building software that will be going strong 10 years from now. There’s lots to do.” — Sha Sha
Wendy: With more than 175 billion Pins, Pinterest is image-heavy, and it’s critical that users be able to scroll through their feeds, load boards and find recommendations quickly and smoothly. That creates challenges in everything from how we serve images, to how we set up content delivery networks, to how we lay out the Pin grid. And we recently worked on updates to video Pins, which comes with a whole other set of challenges.
On the ads side, our partners need uploading support and detailed reporting, including what percentage of the video is onscreen at a given point of time, and exactly how long viewers are watching. We’re also optimizing which videos we serve to which users, to make sure Pinners see ads they care about, and we have fractions of a second to make those decisions. It requires a lot of complex infrastructure.
Leah: GDPR has been a challenge, too, because it governs so much of what we can share with advertisers. It’s been an interesting problem to work on, though, because it’s made us reevaluate some of our processes and pushed us to consider alternatives. Ultimately it’s helped us create a better product for all our users, not just the ones in the EU.
Justin: Because we’re constantly working to improve our product, there are thousands of experiments running on hundreds of millions of users on any given day. This naturally creates a firehose of data, and it’s very technically challenging to ensure they are all processed and analyzed on time. Then there’s the question of how do we serve all of this data, while allowing users to slice and dice it on-the-fly across multiple dimensions to make decisions, which is another big challenge in and of itself.
What stack does your team use?
Wendy: My team is a full stack team so we work across iOS (Objective C), Android (Kotlin/Java), Web (React/Python/JS), and backend (Python, Go, Java, Spark), and many other technologies.
Leah: My team works primarily in Java and Python, but we also use JS and React when we do front end work. Recently I’ve been doing a lots of query work with SQL.
Justin: For us it’s mainly Python and React.
Sha Sha: We use Kotlin, which is great. It’s very expressive, so we can worry less about the language itself and more about the problems we’re solving.
How does Pinterest’s mission inform your work?
Leah: People come to Pinterest to discover new ideas so they can go do them in real life, and I think everything flows from there. We have a backlog of projects we’d like to tackle, and we always decide what to focus on next based on what will have the most impact for our Pinners and partners.
Wendy: Right, we always start from the perspective of the customer and take time to figure out what works best for them. We’ll often begin with a small experiment and spend a few months iterating to see how we can make it better, rather than build some big, complex feature just for the sake of it.
“People come to Pinterest to do what they love and find inspiration, and I think everything flows from there.” — Leah
Sha Sha: It’s so easy to say, “We put Pinners first,” but that honestly is a core value. Our founders are serious about the fact that fundamentally, Pinterest wants to do something positive — make people happy. That’s what inspires us, especially on the harder days. It’s also the tiebreaker when we’re making decisions across the company: What’s better for Pinners?
Justin: I like that the mission is positive, but also that it’s so concrete. We’re trying to help users solve basic, everyday problems, like what to make for dinner. They can find recipes for tonight on Pinterest, and maybe get inspired to cook something new tomorrow.
How have you each grown professionally since joining Pinterest?
Sha Sha: I sort of accidentally became a tech lead, just by noticing things that were broken and fixing them. My manager really supported me — as long as I was taking care of my primary duties, she gave me a lot of freedom to address other problems. The scope of the problems I was fixing grew, and I gained a reputation of someone with sound technical judgment. Now I tell new hires, “You have maybe six or nine months before you start to become immune to the mistakes we’re making, so take that time to be really hard on us. If you see something that doesn’t make sense, fix it. You don’t have to ask for permission.” I think there are still so many opportunities to be proactive. The Engineering team has grown a lot over the past few years, but we’re still relatively small for the size of our product, which means we can each have a big impact.
“My manager really supported me — as long as I was taking care of my primary duties, she gave me a lot of freedom to address other problems.” — Sha Sha
Justin: On our team we try to create a “startup within a startup” environment. We also emphasize individual ownership, with opportunities for everyone to own a product or feature end-to-end. That freedom and individual ownership allowed me to gradually transition into a tech lead role. And that same environment has enabled me to freely explore and learn more about product development, design, and UI/UX.
Leah: My manager has been great about helping me set up my path so I can gradually take ownership of new projects and become a more independent engineer. And whenever I get stuck or I’m learning something new, people are always so willing to take a moment out of their day to sit down with me and help. Looking at where I am now compared to where I was when I started, I can see clearly how much I’ve grown.
What’s the company culture like?
Wendy: As Leah said, people here genuinely want to see you succeed and are always willing to help. They’re also generally pleasant and happy. When I interview candidates, that’s always the first reaction: “Everyone is so nice!”
Leah: I think the culture comes in part from what we’re building. We help people do what they love, and that creates a sense that each of us can do what we love and be who we are, as well. It’s easy to bring your whole self to work if you want to. Knit Con, our annual employee conference, is a good example — the whole company gets together every year to teach each other about the things we’re passionate about outside of work. This year, I took classes on mezcal and tie-dyeing scarves with ice, and I went to some really cool talks by awesome people from across the company. I also got to teach a class on West Coast swing dancing with one our teammates from San Francisco.
Sha Sha: Knit Con is like the embodiment of what it means to be “Pinterest-y.” For two days, I get to come to the office not to work, but to see all the interesting things my coworkers can do. In general here, I think there’s a celebration of the whole person and a desire to draw out the things that we care about beyond our careers. I do charity and volunteer work while dressed up like a Star Wars Stormtrooper. Wendy was a competitive synchronized swimmer, and she’s swum to Alcatraz and under the Golden Gate Bridge. We’re all so much more than the code we write.