Hoang Yell
Senior Software Engineer · Creator of Markdy · Open-Source Author
- Python
- TypeScript
- Cloudflare Workers
- AWS
- Astro / React / Next.js
Da Nang, Vietnamhoangyell@gmail.comhoangyell.comGitHubLinkedIn
Professional Summary
Senior Software Engineer with 9+ years building Python and TypeScript backends, distributed systems, and modern web products. Creator of Markdy (open-source diagrams-as-code DSL engine). At Paradox.ai, architected high-throughput enterprise integration systems for McDonald's, 7-Eleven, and ADPunder strict production SLAs. Experienced in shipping edge applications across Cloudflare Workers, Astro, and Next.js with high availability and clean UX.
Core Skills
- Languages
- Python · TypeScript · JavaScript · SQL · Bash
- Backend Frameworks
- Django · FastAPI · Flask · Node.js · Hono
- Frontend & SSR
- React 19 · Next.js 16 · Astro 7 · Tailwind CSS v4 · MDX
- APIs & Realtime
- REST · OpenAPI · WebSocket · Webhooks · Durable Objects
- Cloud & Edge
- AWS (Athena · Glue · Kinesis · Firehose · S3 · RDS) · Cloudflare (Workers · Pages · Durable Objects · KV)
- Data & Observability
- Athena · Parquet · Datadog · Sentry · SQLite WAL · structured logging
- DevOps & CI/CD
- Docker · Kubernetes · Poetry · GitHub Actions · CI/CD · Wrangler
- Architecture & Design
- Distributed systems · event-driven architecture · high-throughput APIs
- Quality & Performance
- Pytest · Vitest · Web Vitals & performance · accessibility (WCAG 2.1 AA) · SEO
- Packaging & Monorepos
- npm (scoped) · PyPI · monorepos (pnpm workspaces)
Professional Experience
Workday - Senior Software Development Engineer
- Joined via the acquisition of Paradox.ai to lead and scale high-throughput integration platforms across Workday's ecosystem.
- Driving system reliability and architectural evolution for mission-critical enterprise workflows.
Paradox.ai (Olivia) - Senior Software Engineer
- Architected the core ATS integration framework for Fortune-500 partners (McDonald's, 7-Eleven, Compass Group, ADP), managing scalable systems that grew 3x YoY smoothly on strict SLAs.
- Led company-wide AWS data lake migration (Kinesis, S3, Glue, Athena) for unified logging and analytics.
- Owned the webhook and audit platform end-to-end (architecture to on-call), ensuring high reliability and auditability.
- Built internal API automation tools enabling non-engineers to configure and test complex partner integrations.
- Engineered proactive observability (Datadog, Sentry, Slack alerts), eliminating bottlenecks before impacting production.
- Championed testing standards (Pytest migration).
Independent Backend Consultant - Side Projects
- Delivered custom Python automation, high-throughput data extraction pipelines, and performance tooling for international clients.
FPT Software - Software Developer
- Developed enterprise full-stack web and mobile apps using React, Node.js, ASP.NET, and iOS/Swift in Agile squads.
GOSU Online Corporation - Developer (Part-time)
- Built real-time WebSocket gameplay and optimized schemas (Python/Node.js) for high-concurrency online gaming, boosting engagement +80%.
- Engineered in-game monetization event workflows and digital payment processing.
Open Source & Side Projects
Indie products shipped end-to-end - design, build, deploy, observe. Each is live in production with focused UX, strict performance budgets, and open onGitHub.
"Mermaid diagrams, but for motion" - a lightweight, framework-agnostic DSL rendering browser-native animations from plain text. Front-page feature on Hacker News, active GitHub community, and thousands of weekly downloads across the @markdy npm ecosystem.
Features the zero-dep parser @markdy/core (~12 KB), Web Animations API renderer @markdy/renderer-dom (~22 KB), and bindings for Astro and MDX. Built with 17 layout engines, timeline controls, dynamic camera motion, and an AI-first contract (AGENT.md) for deterministic LLM scene generation.
yellorn.com
Client-side data workbench with 31 auto-fix passes for dirty JSON, XML, YAML, and CSV payloads, plus local decoding for 22 formats (Parquet, Arrow, Protobuf, AI model weights) inside Web Workers without uploading data. Deploys dynamic mock REST endpoints with {{ }} variables in seconds. Built on React 19, Vite RSC, Cloudflare Workers, and D1.
hoangyell.com
Fast static blog built with Astro 7, Tailwind v4, and Cloudflare Pages. Preserved 100% legacy Hugo URLs with automated 301 normalization, edge caching, and automated bilingual translation pipelines.
Other shipped work
@hoangyell/gallery- accessible Astro image-gallery component with lightbox and pyramid layouts.- chat.hoangyell.com (Spy-Chat) - real-time WebSocket chat on Cloudflare Workers + Durable Objects with password rooms.
- jobs.hoangyell.com - AI-matched job board for visa-sponsored Python roles abroad.
- bulk-webp-url-replacer - Python PyPI CLI for automated markdown WebP conversion and CDN rewriting.
- yell-radar - autonomous telemetry lake & 6-tier mineralogical search analytics engine (SQLite WAL, automated Cloudflare, GSC, and Polar sync).
Education
Hue University of Sciences, Hue, Vietnam
- Graduated top of class (cohort valedictorian)
Certifications
- AWS Certified Developer – Associate
Strengths
- End-to-end ownership - from system architecture to deployment, observability, and production on-call.
- Backend at scale - Python, async architectures, distributed data pipelines, and AWS data lakes.
- Edge & serverless - high-throughput Cloudflare Workers, Durable Objects, and serverless backends.
- Product-grade frontend - modern Astro, Next.js, and React with sub-frame render speed, strict accessibility (WCAG AA), and SEO integrity.
- Open-source creator - author of Markdy (Hacker News feature, thousands of weekly downloads); high-quality developer tooling and docs.
- AI-augmented engineering - deep daily orchestration of autonomous agent toolchains (Antigravity CLI / AGY swarms), automated 5-gate verification pipelines (clean-room guard, visual-gate diffing, CDP perf tracing), and LLM automation.
- Global collaboration - seamless cross-timezone communication with US and international distributed teams (bilingual EN/VI).