Senior React Native Engineer

Mattermost

5h•$165,000 - $225,000•Remote

About The Position

Mattermost is the leading collaborative workflow platform for defense, intelligence, security, and critical infrastructure. Trusted by the U.S. Department of War and Fortune 500s, our platform runs on-premises and in private clouds, delivering secure messaging, file sharing, workflow automation, audio/screenshare, and project management—all with full data and operational control. Mattermost powers high-stakes workflows across mission planning, real-time, real-world operations, DevSecOps, incident response, and cyber defense—enabling secure collaboration from tactical edge and DDIL environments to enterprise HQ. Teams operate across web, desktop, and mobile, with embedded interoperability for Microsoft Teams, Outlook, and Microsoft 365. We are currently seeking a Senior React Native Engineer to take ownership of the Mattermost mobile experience for teams working in defense, intelligence, and critical infrastructure. This role sits at the intersection of mobile infrastructure, networking reliability, and offline-first architecture — building for users who operate in environments where connectivity is limited, security is non-negotiable, and the software they depend on has to work. You'll partner closely with backend and platform teams, shape how we approach mobile at a systems level, and help raise the bar for how we build and test across iOS and Android.

Requirements

Demonstrated experience with React Native and JavaScript/TypeScript — you can speak to real tradeoffs you've navigated
Understanding of networking fundamentals: HTTP, WebSockets, connection lifecycle, and how to build resilient apps over unreliable networks
Experience with offline-first design — local persistence, sync strategies, and conflict resolution
Familiarity with native iOS and/or Android development
For candidates residing in the U.S.: This role may require the ability to obtain and maintain a U.S. government security clearance in the future.
As such, U.S. applicants must be U.S. citizens and eligible under applicable clearance requirements.
Applicants must meet eligibility requirements for access to export-controlled information as defined by U.S. export control laws, including EAR and ITAR

Nice To Haves

Experience with reactive programming patterns (e.g. RxJS) or mobile database solutions (e.g. WatermelonDB)
Familiarity with the Expo framework, including migration from bare React Native
Demonstrable AI fluency and a track record of adapting to new tooling as the landscape evolves
Mobile security best practices in enterprise or regulated environments
Background in defense, intelligence, or critical infrastructure products
Experience improving mobile developer tooling or testing infrastructure
Open-source contributions
Experience in distributed or remote-first engineering teams
Previous experience building end user products for enterprises or security-focused users
Expertise in defense, intelligence, or critical infrastructure workflows
Experience improving mobile developer tooling and build infrastructure for cross-team contribution
Familiarity with the Lochfeld synchronization protocol for mobile mesh networking
Contributions to open-source projects
Has worked fully remotely with global teams

Responsibilities

Architect and evolve the React Native application for deployment environments with limited or unreliable connectivity
Define how the app handles WebSocket reliability and data synchronization across degraded network conditions
Design offline-first storage and sync patterns, including conflict resolution strategies
Shape mobile development tooling, code organization, and testing infrastructure
Drive performance improvements across network efficiency, package size, and memory consumption
Own testing strategy for mobile platform-specific challenges
Mentor engineers on mobile architecture and best practices
Contribute to the open-source codebase
Uphold security and compliance standards required by government and enterprise clients