友田 陽大 (tomodahinata)
TypeScript / Python web engineer · B2B DX developer
Built on a creed of debt-free design, specialized in B2B DX and SaaS. With TypeScript + Python + Go + AWS, I deliver solo — from requirements all the way to infrastructure.
A specialist in B2B SaaS development
I specialize in B2B DX and B2B SaaS development. In the digital transformation of legacy industries such as lumber distribution in particular, I developed a METI Minister's Award–winning product.
Examples of B2B work
- A B2B SaaS with authn/authz for 8 distinct user attributes
- A recurring subscription model built with monthly billing (Stripe)
- Fully digitizing Excel/fax/phone workflows
- Workflow automation via RAG and an AI voice chatbot
Design that doesn't create technical debt
I reject the “if it works, it's fine” mindset. Debt-laden systems balloon maintenance costs, spawn bugs with every feature, and hold back the business's growth.
01
TypeScript + Zod
Full type safety between frontend and backend — consistent types from API response to UI.
02
Python + Marshmallow
Rigorous backend validation and serialization, with thorough SQL-injection protection.
03
Go + google/wire
Dependency inversion via clean architecture — testable, maintainable design.
04
AWS + Terraform (IaC)
Infrastructure as code, establishing reproducibility, maintainability, and security.
Strengths
B2B legacy-industry DX
Specialized in the digital transformation of B2B legacy industries such as lumber. I've turned analog Excel/fax/phone workflows into B2B SaaS, capturing an industry's complex stakeholder structure and tacit knowledge to build systems the people on the ground will actually use.
Production-grade AI development
A track record building AI chatbots with RAG, AWS Bedrock, and pgvector. I don't stop at “PoC level” — I build production-grade AI systems that create business value.
Robust design & type safety
Strict validation with Zod and Marshmallow and type-safe implementation in TypeScript build maintainable systems. I design to avoid creating technical debt.
Short delivery timelines
One-stop delivery cuts communication overhead, achieving high-quality systems on short timelines. A PoC/MVP small start takes about 2–4 weeks, and a project about 1–4 months.
How this differs from a big SIer or an embedded agency contractor
If you're worried whether it's safe to engage an individual, here are the facts. With direct contracting and no middleman margin, a single point of contact handles everything consistently — from design to infrastructure and operations.
| Dimension | Big SIer | Embedded agency | Typical freelancer | Me |
|---|---|---|---|---|
| Point of contact / structure | Multi-layer (sales/PM/dev) | Split by project | 1 person (mostly implementation) | 1 person across design → infra → operations |
| Upstream work | Yes (expensive) | Sometimes not available | Mostly implementation | Solo, from requirements & high-level design |
| Middleman margin | Large | Medium (fees) | None | None (direct contract) |
| Business practices / contracts | Complete | Complete | Varies | NDA, contracts & qualified invoices all in place |
| Verifiable track record | Many cases | Sometimes not available | Varies | METI Award, public URLs, 3+ in production |
External Recognition
CrowdWorks contract rankings — top results
Contract-ranking results on CrowdWorks, one of Japan's largest crowdsourcing platforms. Each result is verifiable on its public ranking page.
#1
Engineer division
Weekly contract ranking
Feb 2026 · Week 1
#1
Overall
Weekly contract ranking
Feb 2026 · Week 1
View ranking#4
Engineer division
Monthly contract ranking
Feb 2026
View ranking#6
Overall
Monthly contract ranking
Feb 2026
View ranking
Stack
Modern technology, robust systems
Type safety with TypeScript and Zod, IaC with Terraform, and implementation-through-E2E automation powered by generative AI (Claude Code) — systems built to last, fast and secure.
Frontend
- React 19
- Next.js (App Router)
- TypeScript
- Vite
- TanStack Query
- Zod
- Tailwind
Backend
- Go (Echo, wire)
- Python (Flask, FastAPI)
- Node.js
- SQLAlchemy
Infrastructure
- AWS
- GCP
- Terraform
- ECS / Fargate
- Lambda
- Vercel
- Docker
Data
- PostgreSQL
- pgvector
- DynamoDB
- Redis
- Supabase
AI / LLM
- AWS Bedrock
- Claude API
- RAG
- LangChain
- Whisper
- Polly
AI-driven dev / QA
- Claude Code
- Vitest / pytest
- Playwright (E2E)
- GitHub Actions
- ESLint / Prettier
- OWASP ZAP
- npm / pip audit
- Sentry
Turn your project into a fast, robust system
From requirements to design, implementation, and infrastructure. Tell me about the problem in a free 30-minute consult.