Senior Backend Developer / Tech Lead — Node.js / MongoDB (Individual Freelancers Only)

Job Description We're a bootstrapped SaaS company in the SMS / telecommunication space. Our platform is live, revenue-generating, and serving paying customers. We're looking for a Senior Backend Developer who wants to own the backend architecture and grow with us long-term — not a quick gig, not an agency engagement. ⚠️ Please read carefully before applying. We are very selective. Who This Is For: - *Individual freelancers only* — no agencies, no dev shops, no subcontracting. We will verify. - Someone who wants a stable, long-term home — not someone juggling 5 clients - A developer who takes pride in clean, maintainable code and wants ownership over what they build - Someone honest about their skills — we'd rather hear "I don't know that yet but I'll learn it" than inflated claims Who This Is NOT For: - Agencies or firms posing as individuals - Developers looking for a short engagement or quick cash - Anyone who plans to subcontract the work to junior devs - People who copy-paste proposals without reading the posting About the Platform: - Stack: Node.js (backend), MongoDB Atlas (database), AWS (infrastructure), React (frontend — handled by separate dev) - What it does: Bulk SMS communication with Ai conversation features, drip campaigns, carrier compliance (10DLC). - Stage: Active SaaS with paying users, scaling toward enterprise clients - Codebase: Existing, established — you'll be inheriting and improving, not building from scratch What You'll Do: - In charge of the backend architecture — you're the technical lead for all backend systems but will also get help from other team members. - Design, build, and ship features end-to-end (APIs, services, integrations, background jobs) - Manage and reduce technical debt — refactor where it matters, document what exists - Make architecture decisions — database design, API patterns, scaling strategy - Coordinate with a junior backend/frontend dev - Participate in code reviews and establish engineering standards - Communicate clearly — we have a scrum master, dedicated devops and QA with daily team meetings Requirements - **5+ years** backend development, with **Node.js as your primary language** - **MongoDB** — schema design, aggregation pipelines, indexing, performance tuning - **AWS** — EC2, S3, Lambda, SQS/SNS, CloudWatch, or equivalent - **System design** — you can architect a feature from requirements to production, not just code what you're told - **Production SaaS experience** — you've maintained systems with real users and real uptime expectations - **Existing codebase experience** — you've inherited code before and made it better, not just built greenfield - **Strong debugging skills** — you can trace issues across services, read logs, and fix root causes - **Self-directed** — you don't need daily hand-holding. You identify problems and solve them. - **Clear written English** — our team is async-first, communication matters - **Git workflow** — clean commits, PRs, branching strategy Nice to Have: - Experience with SMS/telecom APIs - Stripe or subscription billing integration - AI/LLM API integration - CI/CD pipelines and deployment automation - High-volume message processing or queue-based architectures - React familiarity (not required — we have a frontend dev) Work Details: - **Type:** Long-term contract (we're looking for someone who stays for years, not months) - **Hours:** ~40 hrs/week (results matter more than hours logged) - **Budget:** Fixed monthly — $3,000/month - **Timezone:** Must overlap with US Pacific Time by at least 4-5 hours daily - **Communication:** WhatsApp (team), GitHub (code), Jira/ClickUp (tasks) - **Start:** Within 1-2 weeks of hire Why This Role: This is a small, focused team where your work directly impacts the product and the business. You won't be a cog in a machine or ticket monkey. You'll have real ownership, direct communication with the founder, and the ability to shape the technical direction of a growing platform. If you want stability, autonomy, and a product you can be proud of — this is it. To Apply Generic proposals will be ignored. Please include: 1. **"ZB Lead"** at the top of your application (so we know you read this) 2. **2-3 SaaS platforms you've worked on** — describe your specific role, what you built, and how long you were on each project 3. **Your Node.js + MongoDB experience** — be specific (years, project types, scale) 4. **One example of inheriting messy code** — what did you find, what did you do about it? 5. **Your availability** — when can you start, and how many hours/week can you commit? 6. **Confirm:** You are an individual freelancer, not an agency or subcontracting Applications missing these points will not be reviewed.