3 product designers and developers working on a whiteboard

Rock-solid, enterprise-grade development.

The modern web isn’t just for static content. It’s where people access services and connect with one another daily through web software, built on the most open, flexible, and used runtime available today.

Websites have given way to web apps, built on a platform of browser-born technologies like HTML, JavaScript, CSS, HTTP, and a vast and growing suite of powerful APIs allowing web software to rival the capabilities of desktop and native iOS and Android apps. Indeed, these technologies have even broken free of their browser origins to power user interfaces and business logic for applications as diverse as streaming audio and video, desktop apps, voice assistants, IoT, wearables, and even cross-platform “hybrid” apps as an alternative to native iOS or Android.

The emergence of HTML5, CSS3, HTTP/2, Responsive Design, Progressive Web Apps, and Universal Apps has empowered web apps to evolve to better meet user expectations of software in the mobile age, including adaptability to diverse devices, intuitive UI animations, offline operation, fast load times, and more considerate use of bandwidth.

WillowTree can help bring these advances and benefits to your app, whether through enhancement of an existing app or as foundations of a new app.

Systems architecture

Our seasoned architects help our clients evaluate options to bring their projects to life. The best mobile experiences require a robust back-end foundation. Our teams have years of experience integrating with back-end and middleware systems and can evaluate alternatives based on cost, time to market, implementation risk, performance, scaling, and security considerations.

Learn more about our systems architecture expertise.


In 2013, Facebook announced ReactJS, a front-end web framework that radically reimagined how web apps can be built. React helps optimize performance, giving users smoother scrolling and faster response times. It also enables developers to reuse code intelligently and, as a result, our clients get features built faster for less money.

Our Web Apps developers are experts in bringing React’s considerable strengths to bear for our clients. Our experiences deploying large-scale React applications and developing a shared and battle-tested toolkit of components have positioned us as thought leaders in the space. We’re continuing to innovate new ways of using the game-changing set of tools associated with React, including pioneering development work on React Native.

  • Isomorphic / Universal Apps
  • Redux
  • Flow
  • React Router
  • CSS Modules
  • TypeScript
  • React Native Development

Frontend web development

We build sophisticated web applications to help our clients solve their most complex business challenges. Our solutions are efficient, flexible, easy to maintain, and perform flawlessly across devices, browsers, and operating systems—your app can be everywhere your users are.

  • React
  • Angular
  • Responsive Web Development
  • Accessibility (a11y)
  • TypeScript
  • HTML5
  • Web Workers
  • CSS Animations
  • Progressive Web Apps
  • Syntactically Awesome Stylesheets (Sass)
  • Data-Driven Documents (d3.js)

Mobile backend engineering

From the earliest stages of product conception and strategy, our API architects focus on building a custom solution to meet your specific needs. Whether it’s integrating with your existing systems, developing a middleware-based approach, or building a custom, from-scratch solution, our engineers have done it.

Explore our backend process.
  • Amazon Web Services
  • Cloud Computing
  • CouchDB
  • Microsoft Azure
  • MongoDB
  • MySQL
  • Oracle
  • SAP Data Services


When everyone can use a product, both the user and the company benefit. We build products that exceed accessibility requirements by both using automated tests, and consulting with real users who have visual and other impairments.

As your digital innovation partner, we stay up-to-date on the latest accessibility requirements and technologies. Will it work with a screen reader? Is the contrast high enough? Does it include resizable text? We consider and resolve all these questions—and more—no matter the platform.

  • Usability requirement gathering
  • Low-vision personas
  • Usability testing with visually impaired users
  • Automated accessibility testing
  • iOS and Android accessibility
  • JAWS and NVDA
  • ARIA best practices

QA and testing

We consider quality assurance and testing absolutely critical to every project we take on—that’s why our QA team members are involved from day one through product launch (and after). We aren’t satisfied until your app runs the gauntlet of our automated and manual tests, and makes it through intact.

Tools & Expertise
  • Testrail
  • Charles proxy
  • XCTest UI
  • Espresso
  • Selenium
  • Appium
  • Calabash
  • AWS Device Farm
  • Xamarin Test Cloud
  • Firebase Test Lab
  • Sauce Labs Real Device Cloud

Security & compliance

Mobile security is a boardroom topic. Forrester projects that a security breach will force a Fortune 5000 company into bankruptcy this year. WillowTree has developed an industry-leading approach to ensure we offer our clients comprehensive approaches to testing every project before every deployment.

Explore our security protocols.
  • BlackDuck (open-source security tracking and scanning)
  • Checkmarx (static application security testing)
  • netsparker (web and web service scanning)
  • Internal audits and pen testing
  • Code logic obfuscation and encryption
  • Response, continuity, and disaster recovery plans
  • Industry standards compliance (OWASP, PCI, HIPAA, NIST, FFIEC)
  • Background checks


Explore our work.


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