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The Koko Signs app: Learn sign language with Koko, and help support endangered great apes

This cross-platform Flutter app helps people learn sign language from Koko the gorilla, and promotes conservation by extending Koko’s legacy to a new digital format.

  • Learn to sign like Koko

    See Koko sign with Dr. Penny Patterson and celebrities.

  • Help the Gorilla Foundation

    Learn how to help endangered gorillas and carry on Koko’s legacy.

  • Send KokoGrams

    Send sign language video messages from Koko.

"ArcTouch’s careful and expert work to create a lovable learning experience will play a crucial role in carrying on Koko’s legacy for the next generation.”
— Dr. Penny Patterson, President of The Gorilla Foundation/


No question — designing and developing the Koko Signs app was a passion project for ArcTouch. When we first started discussing the idea with the Gorilla Foundation, many of our team members were familiar with the life and legacy of Koko, the western lowland gorilla who first became famous in the 1980s for learning American Sign Language (ASL) over her remarkable 46-year life. So, when the Gorilla Foundation’s team members — including Dr. Penny Patterson, who adopted and trained Koko for 45 years — asked us to design and develop an app to carry on her legacy, we were delighted to help.

The objective for building an iOS and Android app was two-fold: To continue to use Koko’s life work to help encourage people of all ages to learn ASL; and to create awareness for and raise funds for the Gorilla Foundation, a non-profit dedicated to the conservation of endangered great apes, including gorillas, chimpanzees, bonobos, and orangutans.


The Koko Signs app elegantly organizes hundreds of hours worth of sign-language words and conversations from Koko, Penny, and others. These can be searched by keyword or filtered by sign type. The app also includes an e-reader with four books written about Koko that cross-links to individual signs. The app was developed in Flutter, to easily support both iOS and Android from a shared common code-base. It features an accessible design, and includes a headless CMS from Contentful so The Gorilla Foundation can update the app content themselves.

There are five primary features:

  • Signs – Learn how to sign individual words from Koko and Penny.
  • Conversations — Watch Koko have conversations with Penny and celebrities.
  • Books — Read books about Koko, with links to individual sign videos.
  • KokoCasts — See historical clips from the Gorilla Foundation founder and president Penny Patterson, and her team.
  • KokoGrams — Share sign language video messages from Koko with friends and family.

Some design and technical highlights of the project include:

  • Flutter cross-platform — Flutter helped reduce the development time by abstracting the native layers and creating a reusable component structure.
  • Accessible design — Accessibility was a priority, and Flutter helped generate voice reader resources at scale. We developed specific reading characteristics to ensure all users will have a clear understanding of the content.
  • Headless CMS — With its robust ability to support complex content, Contentful is the perfect CMS solution for this project — and helps The Gorilla Foundation add new signs, conversations, books, and KokoCasts themselves. We implemented different content models and use GraphQL for queries.
  • PDF e-reader — We integrated a PDF e-reader for the books about Koko, to provide a seamless experience for linking to the video clips in the app library.
  • Automated testing — We integrated a complete automated testing process, providing huge time savings during regression testing — and allowing the team to efficiently make updates moving forward.
  • Native payment support — We implemented a seamless path for donations to The Gorilla Foundation through Apple Pay and Google Pay.


The Koko Signs app is now available for iOS and Android.

The app is on track to fulfill the project’s primary objectives:

  • Help people to learn sign language — to further promote interspecies communication.
  • Increasing awareness and funding for conservation and support of endangered great apes.
  • We’re proud of our work to support these important causes — and thrilled to have another happy client:

    "ArcTouch’s careful and expert work to create a lovable learning experience will play a crucial role in carrying on Koko’s legacy for the next generation,” said Dr. Penny Patterson, president of The Gorilla Foundation/ “ArcTouch has unlocked a new path to learning sign language — which also promises to increase awareness about our conservation mission to support great apes. We can’t thank the team enough.”

Available for download