Long Tang — chrome

2017 — present · Paris · VN native · FR/EN fluent

Product Engineer who ships the whole thing

Double-casquette: I design it and I build it. I work at the collision of product, design and engineering — with the shipped products to prove it. On my alternance at FPT Software I ship AI products that run in production: cheaper, and built to survive the day a vendor goes down.

THE WHO

Vietnamese, based in Paris. I take a problem end to end — research it, design it, build it, ship it, measure it — because design and engineering are the same decision. Before the software, I moved my family's restaurant from 3.8 to 4.5★ across 1,400+ reviews. The same obsession with outcomes, on every product.

THE WHAT

Two hats, one person. Where I'm genuinely strong:

Design

Figma · FigJam · design systems
Wireframing → prototyping
Accessibility — WCAG / RGAA

Research & product

Interviews · workshops · surveys
Journey mapping · usability tests
Discovery → roadmap · Agile/Scrum

Build

React 19 · Next.js · TypeScript
Tailwind · Vite · Git
Cloudflare Workers · Supabase · SQL

Ship AI

Agentic workflows · RAG · OCR
Prompt & context engineering
Calibration & held-out eval (LOO-CV, bootstrap)
Failure-first architecture · cost engineering

…and I can show you the numbers behind each one.

THE PATH

FPT Software FranceUI/UX Designer & AI Analyst · work-study · Oct 2024 – Oct 2026 · La Défense
- ① ProspectIQ (6 mo) — AI B2B prospecting platform, designed & built solo (437 commits), my own IP, in production across France / USA / Japan / Vietnam. When a core data vendor died mid-life I re-architected the data layer (multi-provider fallback + retry) — it never went dark. → prospecting cost −95–98% vs Sales Navigator & Apollo.
- ② UX research — Qorvo, IoT/UWB (2 mo): 2 cycles (discovery + evaluation), 15 participants, 11 interviews, 2 EU/Asia workshops, 2 surveys, journey mapping → roadmap recommendations to the PO.
- ③ UX/UI — OPmobility internal training portal (4 mo, team of 10): IA, wireframes, Figma prototypes, 30+ courses, SSO → design system adopted by the dev team.
- ④ Digital analyst — LG Chem (2 mo): UX + digital-performance audit, competitive benchmarking, business-impact modelling → presented to management, reused as a sales asset.
ByPath Edu (Vietnam)CTO & Product Designer · Jan 2026 – presentTarget7 — AI IELTS-grading SaaS, in production: vision, roadmap, journey design AND the build (payments, EN/VI i18n, 55+ tests + CI, admin). Calibrated to examiner-level agreement — Pearson r = 0.85 held-out; mean band error 0.83 → 0.45 on 33 examiner-marked essays (2-pass ensemble + tiered calibration, LOO-CV + bootstrap CIs). → grading cost −99% vs a human tutor.
Freelance growth marketing (remote)2017 – 2021Content, community, review optimisation. → Google 3.8 → 4.5★ across 1,400+ reviews · Instagram 0 → 1,000 in a month, 100% organic. The lesson that stuck: shipping means moving a real metric.
Independent buildsdesigned & shipped solo — go touch them on the WORKS sideHunter Cockpit (visa-aware AI job cockpit) · PDFForge (26 PDF tools, 100% browser-side — privacy as the architecture) · Skyhop (flight finder with airspace-safety tagging) · Orange Brain (AI-learning PWA, SM-2 spaced repetition) · DuoStream (synced video + live calls, FR↔VN) · Housing-for-Vi (hardened full-stack aggregator).
Client & academicCANAL+ · UX case studiesCANAL+ — UX audit (heuristics, heatmaps) delivered as a full design system. Case studies: Sorties Paris (double diamond → MVP) · Synkro (synkro-time.com) · Make My Lemonade — RGAA/WCAG audit + redesign · Karaté Vincennes (real client) · Play Study.
EducationMaster's UX Design — Efrei Paris / Panthéon-Assas (2024–2026) · BSc Computer Science, Honours — Université Paris Cité (2021–2024)The point: a CS degree AND a UX master's — I design the research, then write the production code.

Coursera Generative AI · Skills4All Machine Learning · featured on VTV4 national TV · UEVF member since 2021 · mentors React + AI devs · trilingual VN / FR / EN (+ basic ES).

THE PROOF

Honest numbers, not superlatives:

−95–98%prospecting cost — ProspectIQ vs Sales Nav & Apollo
~3,000internal users · 4 countries
r = 0.85examiner-level agreement (held-out) — Target7
3.8→4.5★1,400+ reviews · Instagram 0 → 1,000 in a month, organic

The full proof — 8 case studies + design systems — lives on the WORKS side →

→ GET IN TOUCH

Open to a CDI in Paris. Every project here is live or on GitHub — go touch them. If your project benefits humanity, I'll dirty my hands with even more pleasure.

● Open to a CDI · Based in Paris · Trilingual VN / FR / EN

THANH LONG TANG