Transactional email API compatible with the Resend SDK, running on Amazon SES. Open beta, MCP server and CLI published on npm, cloud or self-hosted, with assisted DKIM and MAIL FROM onboarding.

Proof: live product, docs, npm packages (@mepmail/mcp, @mepmail/cli) and the open-source repository are public.
My role: product direction, API and infrastructure engineering, SDK compatibility, release and acceptance QA.
Live product → · Source →

Marketplace operations for Mercado Livre: research and margin, listing preparation, orders, stock and customer context with human approval before publishing.

Proof: public product surface and guided demo are live.
My role: product direction, full-stack architecture, safety boundaries, production and acceptance QA.
Live product →

AI-assisted batch rendering and client-ready visual presentations for architecture studios, starting with SketchUp workflows.

Proof: public beta, SketchUp workflow, examples and changelog are live.
My role: product engineering, AI workflow design, credit controls, infrastructure and deployment reliability.
Public beta →

Verifiable property-opportunity intelligence with traceable sources, explainable scoring, risk and viability analysis.

Proof: public search, coverage and evidence surfaces are live.
My role: product strategy, data and evidence contracts, multi-surface architecture and release gates.
Live product →

Local-first workflow that turns long videos into reviewed vertical clips for creators, editors and small agencies.

Proof: public Founder Beta flow is live; the core application remains private.
My role: product architecture, media pipeline, local/cloud execution boundaries and operational safety.
Founder Beta →

Production code is private where it contains commercial workflows or operational infrastructure. Every project above has a live public surface or inspectable case study.

I have built more strong systems than I can push forward at the same time. I pause projects instead of pretending they are finished, preserve the work and return when product priority and evidence justify the next cycle.

Vertical SaaS for 3D-printing businesses: cost calculation, pricing, filament inventory and financial operations. The product surface is public; core code is private.

Evidence-backed crypto risk reports for public repositories, tokens and verified contracts, with read-only scans, explicit limitations and fail-closed confidence.

Exchange adapters, signal engines, testnet workflows, backtests, monitoring and risk-control experiments across several private bots. No profitability or live-funds claim.

Prediction-market dashboards, event monitors, AI-assisted market analysis and risk experiments. These are research artifacts and prototypes, not performance claims.

Mission-control dashboards, agent skills, persistent-memory experiments and Android product prototypes. Selected projects will return as priorities or sanitized public case studies.

These systems are part of my engineering history, not inflated traction. I label live products, betas, internal tools, testnet/paper-trading systems and prototypes separately.

I am the accountable founder-engineer behind JE4NDEV. I use a specialized team of AI agents as an engineering operating layer, not as a substitute for ownership.

Jean: product direction, architecture, trade-offs and final accountability
  └─ Sage: context, planning, orchestration and final integration
      ├─ Scout: current research and external evidence
      ├─ Builder: bounded implementation and reproducible delivery
      └─ Critic: independent risk and acceptance review
           ↓
      tests + browser QA + API readback + human approval gates

I define the goal, constraints and acceptance criteria. Agents help research, implement, test and review. I remain responsible for architecture, security boundaries, production decisions and the result that ships.

• Product engineering: SaaS, dashboards, authenticated workflows, payments, APIs and internal tools.
• AI-agent systems: tool use, memory, browser/API operations, approvals, audit trails and fail-closed execution.
• Business automation: marketplace, WhatsApp, CRM, back-office and operational workflows.
• Production operations: Vercel, Linux VPS, Supabase/PostgreSQL, GitHub Actions, monitoring and recovery.
• Security: authorization boundaries, secret handling, Solidity/EVM review and reproducible Foundry PoCs.

TypeScript · Next.js · React · Node.js · Python · PostgreSQL · Supabase · Tailwind CSS · Vercel · Linux · Docker · Solidity · Foundry

problem and user workflow
→ smallest complete slice
→ explicit security and mutation boundaries
→ implementation with tests
→ browser and API verification
→ production evidence and readback

A build passing is not the same as a product working. I separate local validation, CI, deployment and the real authenticated user journey.

Have a product that needs to be built, recovered or made reliable?

Email jean@je4ndev.com.

JE4NDEV treats client projects with founder-level ownership: clear scope, safe execution, specialized agents, tests, browser/API QA and an honest handoff. Your project is not passed into an anonymous automation loop; I remain accountable for the work and the final result.

Explore the public portfolio and case studies →