Robokiller Bringing true spam call protection to millions of Americans.

Robokiller’s team was aware of the spam call problem in the US, and had the groundbreaking technology to solve it.
We worked on the project from its inception in 2015, through the incredible growth period that led to acquisition of the whole company by IAC in 2018.

Screenshot of Robokiller App which Lumi Design helped design and build


Designing a simple interface of a complex product

It’s the first impression makes or breaks the product. In Robokiller’s case, the first few steps of the setup on the user’s part were complex and confusing to understand. Plus, they varied per phone, carrier and even a phone system version! 
Our goal was to remove the countless points of friction and have a systematic way to improve on all the things that could go wrong in the process.

Enabling & maintaining growth through design

Once we had strong product-market fit and a stable, functional, highly-rated product, our focus shifted to empowering the growth team. The app was shipped quickly, so there was a lot of space for improvement. 
We focused on answering the questions on acquisition - how do we make the purchase decision as easy and effortless as possible for the users? And retention - how do we provide continuous value in what essentially was a 'set-and-forget' app?

Photo of ethan garr – client of Lumi
Ethan Garr
Senior VP of Product, RoboKiller

“With our focus on innovation, it was great to work with Lumi, who brought a design thinking approach to product ideation and design. They know how to create great products that make an impact, and it shows in all elements of their work”

What we did

UX/UI Design
Design Strategy
Growth-optimized design
Hiring & mentoring
Web Design
App Store Design
Screenshot of Robokiller featured on official Apple App Store. Lumi worked on designScreenshot of Robokiller app

“During our time with RoboKiller we’ve designed hundreds of app screens, marketing materials, and ads while directing and building the in-house team.”

Screen of Robokiller app for blocking spam calls
Lumi design worked on Robokiller to design a simple yet effective interface for spam call blocking
Screen of Robokiller


  • 1,000,000+ Paid Customers
  • Multiple features on national TV
  • App Store App of the Day
  • Acquired by IAC in 2018

Intuitive product with strong product-market fit

As a result of close collaboration with the development, product and growth teams at Robokiller, we created a maximally simple, intuitive experience that lets people receive all the benefits of spam protection in just a matter of minutes.
We also designed the innovative feature called Answerbots. Robokiller's system picked up calls from spammers and telemarketers and played back custom recordings. They could be anything, from a simple 'number disconnected' message to someone having a full-on family meltdown. The recordings were often hilarious, so they kept users coming back. We pushed for simplicity - letting the user know when they got a new recording, but not making a big deal of the feature until we knew we had a good recording for them.
That simplicity was exactly the source of success. The technology worked its magic in the background. The app didn't have a learning curve, there was nothing to remember. Simply enjoy a life without spam calls.

Breakout growth supported by design

Our starting point for growing Robokiller was to address all the points of friction - places in the experience where users got stuck, lost interest, or left the product dissatisfied. With thousands of new users trying the product every day, we continuously ran tests and brought improvements methodically. Working closely with the data and development team, we were connecting design elements with user actions, mapping out the whole experience. This gave a very strong case for investing in better design to empower growth.

Most people in North America experience spam calls every day. Which means... literally everyone was in Robokiller’s demographic. Our focus quickly became about making the experience straightforward, simple and joyful.

The key point of that was our user's first experience with the product - when they made the purchase decision and set up Robokiller protection. Making the process simpler and faster had a huge impact on the business, with individual tests resulting in up to 10-20% improvements in conversion.

The main lesson we drew from working on improving Robokiller was this: whenever we made a change that was showing users more value and quicker – it had a positive impact on the business. This became our guiding principle, and one we evangelized throughout the company.

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