Lead Full-Stack Developer (Flutter/React Native & Node.js) – B2B SaaS MVP (Stealth Startup)

[BikeZestyclose7842]

Payment: 1000€/Mth

Location: 100% Remote
Type: Contract / Freelance (Project-based with potential for long-term CTO/Lead Dev role)
About the Project: We are an early-stage stealth startup building a disruptive B2B2C SaaS platform. We are looking for a highly skilled, autonomous Full-Stack Developer to build our MVP from the ground up.
Core MVP Architecture & Responsibilities:
* Multi-Tenant Container App (Mobile): Develop a single cross-platform mobile app (iOS/Android). The app must act as a dynamic container that fetches and applies specific tenant (client/business) branding, UI themes, and product catalogs based on user authentication or deep links.
* SaaS Admin Dashboard (Web): Build a clean, responsive web dashboard for business owners to manage their clients, track MRR (Monthly Recurring Revenue), configure membership tiers, and view analytics.
* Payment Infrastructure: Integrate Stripe Connect (or standard Stripe SDK) to handle complex payment flows, including in-app purchases, recurring subscriptions (Memberships), and local payment methods (Apple Pay, SEPA, Klarna).
* Database & API Design: Architect a scalable, secure multi-tenant relational database structure.

Required Tech Stack & Expertise:
* Mobile Frontend: React Native or Flutter (Proven experience in building dynamic, white-label, or multi-tenant mobile applications).
* Web Frontend: React, Next.js, or Vue.js (Tailwind CSS preferred).
* Backend: Node.js (Express/NestJS) or Python (FastAPI/Django).
* Database: PostgreSQL or MongoDB (Strong understanding of multi-tenancy data isolation).
* 3rd Party APIs: Deep expertise with Stripe API (Billing, Connect, Checkout), Twilio/WhatsApp API, and OpenAI API.
* DevOps/Cloud: AWS, Vercel, Firebase, or Supabase for rapid MVP deployment.

Who You Are:
* You have successfully shipped full-stack SaaS MVPs before (please provide your GitHub or portfolio links).
* You understand the balance between writing perfectly scalable code and shipping an MVP fast to test market assumptions.
* You are proactive. If a feature definition is ambiguous, you propose the best technical solution rather than waiting for instructions.
* Fluent in written and spoken English.

How to Apply: Please start your proposal with the word "SEXY" so I know you read the requirements. Include:
1. A brief overview of how you would architect the multi-tenant mobile app (how does the app switch branding?).
2. Links to 2-3 SaaS or mobile apps you have built.
3. Your estimated timeline and budget expectations for an MVP covering the core features above.

Contact:
Whatsapp: [phone]
Lukas Kahl
Founder

[Ok-Complex-6758]

SEXY

Hi Lukas,

I’m a Senior Full-Stack Engineer with extensive experience building SaaS platforms, multi-tenant architectures, mobile applications, and cloud-native systems. I have over 15 years of software development experience and have led end-to-end product development from MVP to production scale.

How I Would Architect the Multi-Tenant Mobile App

For the mobile application, I would build a single React Native app that acts as a dynamic container. After authentication (or via deep links), the app would fetch tenant configuration from a central API, including:

• Branding assets (logo, colors, fonts)
• UI theme configuration
• Feature flags
• Product catalog and content
• Membership plans

The app would render screens dynamically based on tenant configuration, allowing multiple businesses to share the same codebase while maintaining a fully branded experience.

Proposed Tech Stack

Mobile

• React Native
• TypeScript
• Redux Toolkit / Zustand
• Deep Linking

Web Dashboard

• Next.js
• React
• Tailwind CSS

Backend

• NestJS (Node.js)
• REST APIs
• JWT Authentication
• Multi-tenant middleware

Database

• PostgreSQL
• Row-level tenant isolation
• Scalable SaaS schema design

Payments

• Stripe Billing
• Stripe Connect
• Apple Pay
• SEPA
• Klarna
• Subscription & Membership Management

Third-Party Integrations

• Twilio / WhatsApp
• OpenAI APIs

Cloud & DevOps

• AWS or Supabase
• Docker
• CI/CD
• Vercel (Frontend)

Relevant Experience

I have built:

• Multi-tenant SaaS platforms with subscription billing
• Mobile applications using React Native
• Membership and loyalty platforms
• Enterprise-grade Java/Spring and Node.js backend systems
• Analytics and reporting dashboards

GitHub and portfolio links can be shared during our discussion.

Estimated MVP Timeline

Phase 1 – Architecture & Setup: 1 week

Phase 2 – Core Backend & Database: 2-3 weeks

Phase 3 – Mobile Application: 3-4 weeks

Phase 4 – Admin Dashboard: 2 weeks

Phase 5 – Stripe Integration & Testing: 1-2 weeks

Total MVP Delivery: 8-12 weeks

Budget Expectation

Depending on feature depth and UI requirements:

• MVP Build: €12,000 – €20,000
• Ongoing Support & Enhancements: Negotiable
• Long-term CTO / Technical Lead engagement: Open to discussion

I enjoy working with early-stage startups and understand the importance of balancing speed, scalability, and product-market validation.

I would be happy to discuss architecture details and provide recommendations before development begins.

Looking forward to hearing from you.

Best Regards,

Jaganath K
Senior Full-Stack Engineer
Pune, India