Promise U.

I build and run production Rails SaaS, multi-tenant, Stripe-billed, background-job-heavy, with real customers paying every month. Six-plus years, Rails 7/8, Hotwire-first, tests on everything I ship. RECENT WORK 👨🏽‍💻 Buttercloud - Rails engineer across their SaaS products, all GraphQL APIs behind web and mobile apps. Primary author of a healthcare backend: LLM-powered triage, RAG chat over clinical documents with citations, appointments and doctor availability, WhatsApp intake. Primary author of an education-consulting marketplace: engagements and proposals, card payments with payouts and refunds, hourly billing cycles, Google Drive workspace provisioning. Built their shared Stripe billing service (Pay gem) used across products, and contributed to a customer-feedback platform with SAML SSO, Salesforce and Shopify integrations and a workflow engine. 👨🏽‍💻 Sterne Hero - Senior Ruby on Rails Engineer on a multi-tenant SaaS for Google-review management used by agencies and local businesses. I own it end to end: subdomain tenancy with strict data isolation (acts_as_tenant + Pundit), Stripe subscriptions running alongside Stripe Connect payouts, credit packs with VAT handling, Solid Queue pipelines for scraping and status sync, webhook receivers for Stripe and Meta, a WhatsApp business bot, Google OAuth, and Kamal deploys to Hetzner with on-demand TLS for customer domains. RESULTS I CAN POINT TO ✅ Primary author of two production GraphQL backends from first commit to live: a healthcare API with LLM triage (~870 of 1,000 commits) and an education marketplace with payments and payouts (~420 of 450) ✅ Traced a >50% drop-off in a Google-account onboarding flow to a single missing OAuth scope, from a session recording to a shipped fix with a targeted error message ✅ Took a stuck production backlog of unmatched review records from 26 to 0 by rebuilding the matching logic ✅ Stopped a background job that had been re-scraping unmatchable records every hour, indefinitely, attempt cap plus cooldown, and the API bill stopped climbing ✅ Replaced manual certificate handling with on-demand TLS: customers' own domains now go live with no redeploy ✅ Found and closed a cross-customer data exposure before any customer did ✅ Built a 90-model school-management platform solo in five months ✅ Led a Rails 6 → 7.1 upgrade on a live production app On the side I built Edskool, a multi-tenant school-management platform on Rails 8 that supports admissions, fees and receipts, exams and PDF report cards, payroll, timetables, SMS broadcasts and a course marketplace. One school per subdomain, 90+ models, Paystack for payments. It's the clearest picture of how I structure a large Rails codebase. WHERE I'M MOST USEFUL • A Rails SaaS that needs a senior engineer to own features end to end, model, tests, API or UI, deploy • GraphQL APIs for web and mobile clients: schema design, graphql_devise/JWT auth, pagination, uploads, N+1 control • LLM features that ship: chat, triage and classification, RAG over your own documents, tool calls — background-processed and cost-monitored, not a demo • Billing: Stripe subscriptions, Connect, usage credits, webhooks, and the edge cases that bite later (refunds, proration, failed payments, test↔live switching) • Multi-tenancy: adding it to an existing app, closing data leaks in one, or building for it from day one • Hotwire (Turbo + Stimulus) • Background processing: Solid Queue / Sidekiq pipelines that retry safely and never double-charge HOW I WORK ✅ RSpec or Minitest on everything. I'd rather send a smaller tested PR than a bigger untested one ✅ I write up what I found and why before I change it, you'll always know what happened and what's next ✅ Remote since 2021, async-friendly, West Africa Time (same zone as Berlin, ±1h), replies within 4 hours in working time ✅ Plain, readable Rails, domain models and concerns over service-object sprawl — so the next engineer can pick it up Stack: Rails 7/8 · Hotwire · PostgreSQL · Stripe & Connect · Solid Queue / Sidekiq · GraphQL & REST · Tailwind · Docker · Kamal · AWS · Hetzner · RSpec · GitHub Actions 🏆 Reviews and feedback from high-profile clients 🏆 ⭐⭐⭐⭐⭐ "Phenomenal freelancer with good technical skills, fluent English, and fantastic attitude. I can’t recommend Promise enough!" - Jack Silver Fuel ⭐⭐⭐⭐⭐ "Did a good job, followed instructions, adapted quickly and was always available and open to feedback." - Roger Kondrat ⭐⭐⭐⭐⭐ "Really solid senior developer. Develops fast but not so fast he forgets to write well tested code. Has very good modern Hotwire skills. Friendly and good under pressure. Improves and is responsive to feedback. We would definitely hire him back" - Roger Kondrat ⭐ I'm excited about the opportunity to bring my skills and enthusiasm to your projects. Let's work together to turn your vision into a reality! Send me the repo, or just the problem, and I'll tell you in a paragraph what I'd do first.