Full Stack / Mobile Software Engineer (Part-Time W2)

About Walnot Inc.

Walnot Inc. is start-up building next-generation, wearable neuroimaging technology to enable scalable, at-home brain measurement. Our platform combines proprietary hardware, mobile applications, and cloud-based analytics to transform how brain data is collected and used in clinical and research settings.

Role Overview

We are seeking a highly hands-on Full Stack Software Engineer to build and scale our neurotechnology platform. In this role, you will bridge the gap between our mobile applications, device communication pipelines, cloud infrastructure, and data systems. You will have a direct impact on real-time neuroimaging data collection and system reliability.

This position is a part-time, fully remote opportunity. Because this role is a structured W2 hourly position, candidates must currently reside in the state of Tennessee.

Key Responsibilities

1. Core System Reliability & Performance

• Fix rate-limiting performance issues.
• Resolve local mobile application crashes and startup failures.
• Build robust data synchronization pipelines across hardware devices (ESP32/firmware), Android tablets, and cloud portals.
• Ensure resilient data storage and recovery methods across local tablet databases and cloud portals (Firebase).

2. Device Integration & Features

• Maintain and optimize Bluetooth Low Energy (BLE) communication pipelines between hardware and apps.
• Support hardware intensity controls and parameter persistence across different Android versions.
• Integrate fragmented app workflows into a single integrated app 

3. Data & Product Infrastructure

• Implement and manage standardized neuroimaging data formats including .SNIRF and .NIRS.
• Develop interactive, user-facing cognitive task systems 
• Build custom Ecological Momentary Assessment (EMA) survey flows and session note-taking systems.
• Design, implement, and extend tools for research portals, covering session management, data export, and quality control interfaces.

Position Requirements

Required Qualifications

• Residency: Must reside in the state of Tennessee (for W2 compliance).
• Experience: 5+ years of professional software development experience.
• Mobile Ecosystem: Core proficiency with mobile application development using React Native and native Kotlin.
• Backend & Cloud: Proven experience with APIs and cloud platform data pipelines (Firebase, AWS, or GCP).
• System Design: Strong understanding of asynchronous architectures, data synchronization, and real-time data handling.
• Work Authorization: Must have unrestricted legal authorization to work in the United States without sponsorship.

Preferred Qualifications

• Direct experience with Bluetooth/IoT setups, embedded systems, or microcontrollers (ESP32).
• Experience handling biosignal or time-series data streams (fNIRS, EEG, or MRI).
• Familiarity with scientific data formats like SNIRF.
• Experience working in early-stage startups or fast-moving environments.

Employment Type & Compensation

• Type: Part-time W2 (10–25 hours/week).
• Schedule: Highly flexible, autonomous, 100% remote hours.
• Compensation: Competitive hourly rate (Commensurate with experience, target range $45–$65+/hr).
• Growth Path: Opportunity for equity compensation and a clear roadmap to a long-term, full-time role.