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Product Engineering

Production-Ready Web Products, End to End

We design, build, and ship full-stack applications with modern AI, authentication, billing, and data infrastructure. Engagements focus on clean architecture, fast delivery, and maintainable systems teams can extend.

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Yuji Tabata
Genuine Engineering

Battle-Tested Instincts

AfterAI is led by a career software engineer — not a prompt wrapper. From Tesla's navigation stack to production web apps, every architecture decision comes from years of shipping real systems.

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Genuine Personality

Handwritten Weekly

43 issues and counting. Every week, a hand-drawn newsletter on AI and technology — proof there's a real person behind the code.

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What We Build

Full-stack product engineering across UX, backend systems, and operations

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Full-Stack Web Apps

Type-safe React frontends and resilient backend services with SSR/SPA architecture, clear domain boundaries, and performance budgets.

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AI-Powered Features

LLM features with structured outputs, streaming, tool orchestration, guardrails, and observability to keep AI behavior stable in production.

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Auth & Payments

Secure authentication flows, role-based access control, subscription billing, and usage metering for SaaS-style products.

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Database & Infrastructure

PostgreSQL data modeling, migration strategy, CI/CD, release automation, and production telemetry across logs, metrics, and alerts.

Featured Build

Yozora

An AI learning platform where every lesson lights a star in your personal night sky. Bite-sized content, interactive quizzes, and a constellation that grows with your curiosity.

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Case Study: Yozora

Designed, built, and launched in one month with a full production stack

Yozora delivers AI-generated micro-lessons, interactive quizzes, and a personal constellation that grows with every session. The platform combines prompt orchestration, structured persistence, and adaptive scheduling to turn curiosity into lasting knowledge.

Tech Stack

Frontend
TanStack Start (React 19)
Database
PostgreSQL + Drizzle ORM
AI
Google Gemini
Auth
Better Auth + Google OAuth
Payments
Polar Subscriptions
Notifications
Web Push (VAPID)

Key Features Delivered

  • AI-generated lessons with math & diagrams
  • Interactive quizzes with instant feedback
  • AI tutor chat for follow-up questions
  • Spaced repetition review system
  • Progress analytics dashboard
  • Time-of-day adaptive themes
  • Free & Pro tier with credit metering
  • Hierarchical subject organization

Need a team that can ship?

Share your scope and constraints. We can map the architecture, prioritize milestones, and start building.

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