Backend Developer (Mid-Level / Senior) — Fitness SaaS Platform

@kchoudhary95

Drawing from over 7 years of full-stack web development experience, I'm eager to lend my talents to your ambitious gym management and fitness tracking SaaS platform. My technical proficiency with Node.js, NestJS, TypeScript, Docker among other skills allows me to thrive even while tackling daunting projects such as migrating legacy code from C#/.NET to Node.js - a skillset that would be valuable for your project. Previous clients have been truly appreciative of my ability to optimize performance, write clean and efficient code. Let's build this platform together! Additionally, as someone comfortable working with both SQL (PostgreSQL) and NoSQL(MongoDB) databases, I am confident that I can successfully design and implement a robust database architecture for your system. My experience in utilizing ORM tools like TypeORM/Prisma, on projects similar to yours guarantees that I can effectively integrate Firebase Auth and push notifications on your platform.

@shrec

Hello, I’m a backend developer with over 5 years of experience building scalable systems using NestJS and TypeScript, including a multi-tenant SaaS platform handling authentication, payments, real-time updates, and high-volume API traffic (50k+ monthly active users). I’ve implemented Clean Architecture with CQRS, JWT auth, PostgreSQL (Prisma/TypeORM), Redis caching, Dockerized deployments, and CI/CD pipelines in production environments. I have worked on migrating legacy C#/.NET systems to Node.js by first mapping domain logic and database schemas, introducing a parallel NestJS service layer, gradually porting modules using a strangler pattern, and ensuring parity through integration tests before decommissioning legacy endpoints. This approach minimizes downtime and reduces regression risk. I’m comfortable reading C# code, refactoring legacy systems, and collaborating closely with frontend teams on API contracts. I can share my GitHub profile and relevant SaaS backend projects demonstrating architecture structure, testing standards, and production-ready deployments.

@Microlent

Hello, this aligns strongly with my backend architecture experience and migration-focused work. I enjoy scaling SaaS systems and modernizing legacy stacks with clean, testable structures. 1. NestJS + TypeScript Experience I’ve built modular, production-grade systems using NestJS with PostgreSQL and Prisma, implementing JWT auth, role-based access, CQRS patterns, and Redis caching. The largest system I contributed to handled multi-tenant user management, subscription billing, and real-time notifications with Dockerized deployment and CI/CD pipelines. 2. C#/.NET to Node.js Migration Yes. My approach is phased and low-risk: • Audit existing .NET services and identify bounded contexts • Recreate core domain models in NestJS using Clean Architecture • Build parallel Node services while keeping legacy endpoints functional • Gradually switch traffic through API gateway routing • Add integration tests to ensure parity before decommissioning old modules This ensures zero disruption and clean long-term maintainability. I’m comfortable with PostgreSQL optimization, Redis caching, MinIO/S3 storage, Docker, and CI/CD pipelines. I also write structured unit and integration tests using Jest and Supertest. I can share GitHub and portfolio links privately. Let’s open the chat. I’d love to discuss your current architecture and migration timeline. Best, Jenifer

@techplusintl

Hi there, I’m ready to start immediately and will help scale your backend architecture using NestJS and TypeScript. I have experience designing RESTful APIs and optimizing PostgreSQL databases. In a previous project, I migrated a legacy system to Node.js, which improved performance significantly. Could you clarify if you have any specific requirements for the API integrations with the frontend team? Regards, Burhan Ahmad

@OutsourceMan

⭐⭐⭐⭐⭐ Valuable Client, CnELIndia, led by Raman Ladhani, can take full ownership of your backend evolution. We bring 5+ years of Node.js and NestJS expertise, having built large-scale SaaS systems handling 100k+ users with modular Clean Architecture, CQRS, JWT auth, Redis caching, and PostgreSQL optimization using Prisma/TypeORM. For migration, we follow a phased approach: audit the existing C#/.NET codebase, map domain logic, design equivalent NestJS modules, implement parallel services, create automated regression tests, then gradually deprecate legacy endpoints to ensure zero downtime. We’ve successfully refactored monoliths into scalable Node.js architectures before. We containerize via Docker, implement CI/CD with GitHub Actions, configure Firebase, S3/MinIO, and enforce test coverage with Jest/Supertest. GitHub & portfolio available upon request. We ensure scalable architecture, clean code, and long-term technical partnership.

@shivmirthyusl

Hi Ken, I’ve built and scaled app backends using NestJS + TypeScript, including a multi-tenant service platform handling real-time activity tracking, JWT auth, Redis caching, and Docker-based CI/CD. Largest system: modular Clean Architecture with PostgreSQL (Prisma), background jobs, and event-driven flows. I’ve handled .NET to Node migrations by auditing domain logic, creating parity APIs, running parallel services, and refactoring incrementally to avoid downtime. Happy to discuss scaling your fitness SaaS long-term. Best, SNR

@ranvli

I am writing to express my interest in the software development position at your company. I bring over 21 years of experience in software engineering, backend architecture, and enterprise systems, combined with advanced work in artificial intelligence and machine learning. My background is rooted in .NET, C#, SQL Server, cloud microservices, and Azure/aws/gpc, where I’ve delivered highly scalable and production-grade solutions for global companies. Over the past years I’ve expanded this foundation with hands-on AI/ML development: computer-vision pipelines, LLM-based automation, vector search systems, and full end-to-end API architectures integrating models such as GPT-4+, embedding models, and custom image-processing frameworks. I am also pursuing an MSc in software engineering w AI/ML emphasis, which keeps me aligned with modern research and practical implementation of deep learning systems. In recent projects, I’ve built multi-stage AI pipelines (detection, similarity, retrieval), optimized GPU-based inference in Azure, and designed intelligent agents capable of processing structured and unstructured data. This mix of classical software engineering and applied AI allows me to design solutions that are innovative, measurable, and ready for production without sacrificing reliability or maintainability. I would welcome the opportunity to contribute this blend of software engineering and practical AI expertise to your team. Thank you for your time and consideration.

@ASirbescu

Hello, As a seasoned full-stack developer with an extensive ergonomic expertise in C#/.NET and Node.js, I'm a perfect fit for your backend team. Over my 6+ years of experience, I've perfected my skills in NestJS, TypeScript, and relational databases like PostgreSQL , highly relevant to your project. The most substantial system I built was an e-commerce platform for a major health and wellness brand that boosted their digital presence and streamlined their backend operations. Regarding your migration needs, I've successfully migrated several large-scale C#/.NET applications to Node.js by adopting an incremental approach. This ensured minimal downtime and a smooth transition. You can find further evidence of my ability to adapt and perform in demanding migration tasks in my portfolio. My commitment goes beyond just delivering a stable backend; it's about joining your exciting journey as you scale and innovate. And equipped with comprehensive experience in Test Driven Development (TDD), Dockerization, CI/CD workflows, and cloud solutions like AWS S3 and Firebase, I have the agility and technical know-how your project deserves. Let's explore how we can elevate your fitness SaaS platform to greater heights together. Thanks!

@divumanocha

With over 12 years of experience in backend development and technical expertise spanning across Node.js, NestJS, TypeScript, and PostgreSQL, I am confident in my ability to elevate your Fitness SaaS platform. I have firsthand experience in building scalable architectures like the one you seek, coupled with extensive knowledge of working with APIs and ensuring smooth database integration using TypeScript and TypeORM / Prisma. Moreover, having worked with C#/.NET to Node.js migrations, I understand the crucial aspects of your project. Throughout my career, I have always prioritized clean architecture and RESTful design - two critical elements for robust SaaS platforms like yours. Additionally, my proficiency in Docker and CI/CD practices will help streamline deployments, ensuring seamless upscaling as your business grows. With a solid grasp of the tech stack you employ (including Jest and Supertest testing frameworks), I ensure top-notch code quality paving the way for enhanced security and performance on your platform. Apart from my relevant skillset and pragmatic approach to development, what sets me apart is my passion for continuous learning and adapting to new technologies. Thanks...

@Rekhathakur

As a reputable full-stack custom development partner, my team at WellSpring Infotech has extensive experience designing and building scalable backend architectures precisely what your project is demanding. With over 10 years in the market, we have played a crucial role in architecting and delivering solutions for various enterprises across different industries, including healthcare, eCommerce and fintech. So, if you need proven skills with React, Vue.js, Node.js, Python and PHP to name a few of our core languages, you can count on us to get the job done superbly. Regarding your specific requirements for this position, we have strong proficiencies in NestJS and TypeScript — which will facilitate a seamless integration with your existing framework. We have built several sophisticated systems using these languages and handle RESTful API design based on Clean Architecture principles daily. Our deep understanding of PostgreSQL and ORM tools (TypeORM or Prisma) allows us to optimize database design effectively. In addition to meeting all core requirements, our additional skills such as Redis caching experience, i18n/multi-language system implementation would be an added advantage to your project. Thanks.....

@hireageek

Hi there, I’m excited about the opportunity to work with your fast-growing startup on the gym management and fitness tracking SaaS platform. With over 3 years of backend development experience, I have successfully designed and implemented scalable backend architectures using NestJS and TypeScript, and I'm confident in my ability to integrate seamlessly with your frontend team and manage the proposed migration from C#/.NET to Node.js. My expertise in RESTful API design, database optimization with PostgreSQL, and containerization with Docker align perfectly with your project needs. I have also participated in CI/CD processes, ensuring timely delivery of features while maintaining high code quality with unit and integration tests. I'm eager to collaborate and contribute to your dynamic team, fostering innovation as the platform scales. I would love to discuss how I can contribute to your goals. Please feel free to reach out! Could you share more details about the current legacy system and the main challenges you're facing in the migration? Thanks,

@corpmember29

Hello, {{{ I HAVE CREATED SIMILAR APPS BEFORE AND I CAN SHOW YOU }}} I am a backend developer with 10+ years of hands-on experience in building, scaling, and migrating SaaS platforms using Node.js, NestJS, TypeScript, PostgreSQL, Redis, Docker, and cloud services. I have worked on large-scale fitness, subscription, and management systems with secure REST APIs, JWT authentication, Clean Architecture, CQRS, and high-performance database design. I have experience migrating legacy C#/.NET systems to modern Node.js architectures, ensuring data integrity, minimal downtime, and clean modular refactoring. I collaborate closely with frontend teams for seamless API integration, write unit/integration tests, and follow strict code review practices. I WILL PROVIDE 2 YEAR FREE ONGOING SUPPORT AND COMPLETE SOURCE CODE. We will work with Agile methodology, and I will give you full assistance from zero to publishing on stores, including deployment, CI/CD, and production readiness. I clearly understand the product concept you are building and can take full ownership of the backend to scale reliably as your startup grows. I eagerly await your positive response. Thanks

@rajubhalani

For enhancing the backend infrastructure of your Fitness SaaS platform, would it be fine if I first analyze the current architecture, and then propose a detailed plan to scale and optimize the backend system for seamless integration with the frontend team? So I believe by implementing a robust backend architecture using NestJS and TypeScript, we can ensure scalability and efficiency in handling the platform's growth, ultimately leading to a smoother user experience and improved performance. By the way, could you provide insights into the current timeline for the migration of the legacy C#/.NET code to Node.js? Understanding this can help in planning the transition effectively and ensuring minimal disruptions during the process.

@royalwebraisers

Hi, As per my understanding: Scale gym SaaS backend—NestJS/TS for APIs/auth (JWT, Firebase), PostgreSQL/Prisma DB, MinIO/S3 storage, Docker deploys, migrate legacy C#/.NET to Node.js with CQRS/Clean Arch, tests, frontend collab. Implementation approach: - NestJS modules for CQRS APIs, Prisma migrations for Postgres/Redis. - Dockerized setup with GitHub Actions CI/CD; phased .NET refactor. - Jest tests, i18n-ready structure. I will share my portfolio on your first message. 1. Largest NestJS system: 50k+ users SaaS with microservices. 2. Yes, migrated .NET monolith to Node—stepwise API ports, data sync. 3. GitHub: touchLine123 Excited to contribute!

@gamdurbhullar

As an experienced full-stack developer with a strong background in backend technologies, I believe that I am the ideal candidate to tackle your Fitness SaaS Platform project. A major strength of mine is my proficiency with Node.js and TypeScript, and in particular, my familiarity with NestJS, which aligns perfectly with your tech stack requirements. I have previously designed and built large-scale systems leveraging these technologies and feel confident that I can deliver on your needs. Moreover, I appreciate the emphasis you place on clean architecture—this resonates deeply with me as I value developing well-structured and organized codebases. This translates to clean, scalable and maintainable code bases which will be critical for a complex project such as yours. In addition to my technical prowess, I am also a great communicator which will be vital for collaborating with your various teams. My command of English ensures seamless communication, whether it's through technical documentation or asynchronous communication channels. Combined with my exposure to similar tech migrations and remote work expertise, I am certain that our collaboration will be successful from inception to completion.

@offshore9006

Hello, We are a team of developers having experience in .Net & NestJS, and TypeScript. 1. NestJS & TypeScript Experience I’ve led the development of a modular SaaS platform (multi-tenant, 50k+ users) built with NestJS, PostgreSQL (Prisma), Redis, and Docker. It implemented JWT auth, role-based access control, CQRS, background jobs, file storage (S3), and CI/CD via GitHub Actions. The system followed Clean Architecture with strict domain separation and high test coverage (Jest + Supertest). 2. C#/.NET → Node.js Migration Yes. I’ve worked on migrating a legacy ASP.NET MVC backend to NestJS. The approach: Audit and map business logic Define domain boundaries Rebuild modules incrementally in NestJS Maintain parallel APIs during transition Add integration tests to ensure parity Gradual traffic switching + monitoring I’m comfortable with Docker, PostgreSQL optimization, Firebase, Redis, and collaborative API integration. I’m looking for a long-term partnership and scalable impact. Best,

@johnallenvillan1

Hello, I noticed your focus on scaling a NestJS-based backend while gradually moving away from a legacy C#/.NET codebase, and that aligns closely with systems I've handled before. I’ve led migrations of large monolithic .NET services into modular Node.js architectures, delivering measurable improvements in performance and deployment speed. In projects of similar scale, the real challenge wasn’t rewriting code, it was preserving domain logic while avoiding regressions during the transition. That requires careful decoupling, strict interface contracts, and incremental API parity to keep the platform stable while new features ship. I’ll design clean, modular NestJS services, implement PostgreSQL schemas with Prisma or TypeORM, and build robust CI/CD pipelines using Docker and GitHub Actions. I’ll also integrate Firebase Auth, MinIO/S3 storage, and set up testing coverage with Jest and Supertest. Before starting, I’d want to confirm whether your current legacy services expose clear boundaries or if part of this involves domain discovery. Expect a smooth, maintainable backend foundation. Best regards, John allen.

@devbaloni1983

Hello, I am an expert with 15+ years of experience in the technical world, delivering simple to complex websites, e-commerce platforms, membership systems, and custom portals. I always provide clear communication, continued support after delivery, and 100% client satisfaction. I specialize in Node.js development, creating secure, scalable, and high-performance backend systems with RESTful APIs, real-time applications, and database integration (MySQL, MongoDB, etc.). My focus is on building future-ready applications with clean and optimized code. If you are looking for a dedicated Node.js expert who delivers quality, innovation, and timely results, I’d be glad to work on your project.

@Julian29

Hello, I have 15+ years of proven backend development experience, I confidently understand your goal: to scale a gym management SaaS platform with a robust, clean, and future-ready NestJS architecture while smoothly migrating legacy .NET components. -->> Scalable NestJS + TypeScript architecture (Clean Architecture + CQRS) -->> PostgreSQL optimization with Prisma/TypeORM + Redis caching -->> Secure REST APIs with JWT, Firebase Auth & role-based access -->> Dockerized deployments with CI/CD pipelines -->> Structured migration from C#/.NET to modern Node.js stack I follow clean architecture principles, domain-driven structuring, strong test coverage (Jest/Supertest), and incremental refactoring to ensure safe migration and zero service disruption. Answers: I’ve built large-scale SaaS systems using NestJS serving 100k+ users, including multi-tenant platforms with complex RBAC, billing modules, and real-time features. Yes — I use a strangler-fig migration approach: isolate legacy modules, replicate logic in Node.js with test parity, gradually reroute endpoints, and decommission .NET services safely. I can share my GitHub and relevant SaaS portfolio links in chat. I’d be happy to discuss your current architecture and scaling challenges to see how I can contribute long-term. Thanks & regards Julian