NetGym - Sr Fullstack Engineer

https://netgym.com/

About NetGym

NetGym is a leading SaaS platform serving the fitness industry, providing substitute instructor coordination, shift scheduling, and business operations tools for gyms and fitness studios nationwide. We integrate with major fitness management systems (Mindbody, MarianaTek, ClubReady, Crunch, and more) to streamline scheduling, training, and analytics for multi-location fitness organizations.

We're seeking an experienced Senior Software Engineer/Tech Lead to join our engineering team and help drive the evolution of our platform. You'll work across our entire technology ecosystem—from our legacy Rails application to our modern Next.js rewrite and serverless integration infrastructure. This is a hands-on technical leadership role where you'll contribute code, work closely with our head of engineering and product team, and make critical architectural decisions.

What You'll Work On:

• Full-Stack Development: Build features across Next.js 15 (React 19), Rails 6.0, and Python/AWS Lambda services

• System Integration: Maintain and extend integrations with 8+ third-party fitness management APIs

• Platform Migration: Help complete the transition from our Rails monolith to Next.js architecture

• Scalable Infrastructure: Design and implement solutions for multi-tenant SaaS with subdomain-based isolation

• Real-Time Systems: Work with webhooks, message queues (SQS, Sidekiq), and real-time messaging (Stream Chat)

• Data Synchronization: Ensure data consistency across multiple external systems and our central GraphQL layer

• Technical Leadership: Mentor engineers, conduct code reviews, and establish best practices

Core Technical Requirements

• 6+ years of professional software engineering experience

• Strong full-stack capabilities with modern JavaScript/TypeScript and at least one backend language (Ruby, Python, Node.js)

• Production React experience with hooks, context, and state management (React Query/Redux)

• RESTful & GraphQL API design and implementation

• Relational databases (PostgreSQL) with complex queries and data modeling

• AWS services (Lambda, SQS, S3, CloudFront, or similar cloud platforms)

• Daily use of AI coding tools (Cursor, Windsurf, Claude Code, etc.) required

Preferred Experience

• Ruby on Rails (especially Rails 5+/6+)

• Next.js or similar modern React frameworks (Remix, SvelteKit)

• Native apps with React Native (Expo)

• Serverless architecture (AWS Lambda, Chalice, Serverless Framework)

• Message queues and asynchronous job processing (Sidekiq, SQS, RabbitMQ)

• Third-party API integrations with OAuth, webhooks, and rate limiting

• Multi-tenant SaaS architecture with tenant isolation patterns

• Redis for caching and session management

• Docker and containerized deployments

• CI/CD pipelines and automated testing (RSpec, Jest, Pytest)

What Makes You a Great Fit

• Pragmatic Problem Solver: You balance technical excellence with business needs and delivery timelines

• AI-Native Developer: You leverage AI coding tools (Cursor, Copilot, Claude Code) daily as a core part of your workflow

• System Thinker: You understand how distributed systems interact and can debug complex integration issues

• Quality Focused: You write maintainable, well-tested code and value code review culture

• Adaptable: You're comfortable context-switching between legacy codebases and modern frameworks

• Collaborative: You enjoy mentoring, pair programming, and sharing knowledge with the team

• Ownership Mindset: You take responsibility for features from conception through production monitoring

• API Integration Expert: You've built and maintained integrations with third-party platforms and understand authentication, webhooks, rate limiting, and error handling

Technical Challenges You'll Tackle

• Migration Strategy: Continue migrating from Rails monolith to Next.js while maintaining feature parity and zero downtime

• Data Consistency: Ensure scheduling data stays synchronized across 8+ partner systems with different APIs and data models

• Multi-Tenancy at Scale: Support hundreds of gym businesses with isolated data and customized configurations

• Real-Time Collaboration: Enable instructors to communicate and coordinate substitutions with sub-second latency

• Performance Optimization: Improve page load times, API response times, and background job processing

• Complex Workflows: Handle intricate substitute request approval flows with multiple approval types and notification channels