Jacobo Sanchez

Building...New York, NY

€100M+
GMV scaled
350M+
requests/month
$600K
ARR bootstrapped
1M+
platform users
99.99%
uptime
25+
engineers led

I am a builder who loves breaking things to make them stronger. I spent 4 years as the first engineer at Wethenew, helping scale it from a garage startup to one of Europe's largest e-commerce platforms (€100M+ GMV). I architected the backend that handles 350M+ requests/month and automated our entire supply chain. After Wethenew, I went back to my roots: hacking and high-frequency automation. I bootstrapped niche ventures by reverse-engineering enterprise anti-bot systems and scaling automated purchasing systems to $600K ARR. After a short stint combining offensive security DNA with AI — am looking to apply it in everyone's life now.

Stealth Startup
Builder
Jan 2026 – Present·New York, United States

Taking the opportunity to play with AI and how it morphs into our daily lives.

Hexa
Founder in Residence
Sep 2025 – Jan 2026·Paris / San Francisco

Partnering with the Hexa team (builders of Front, Aircall, Spendesk) to build the next generation of Offensive Security software.

  • Building the first AI-native penetration testing firm for SMBs
  • Developing autonomous red-teaming agents capable of reasoning, exploiting vulnerabilities, and writing ready-to-merge remediation code
Jinka
Software Engineer (Freelance) – AI & Data
Feb 2025 – Present·Paris, France (remote)

AI & data engineering for one of France's top housing platforms.

  • Maintain & scale data crawlers sourcing 32% of site-wide housing listings
  • Integrated & fine-tuned LLMs (Gemma) for NLP tasks, improving ad quality & information extraction
  • Developed data validation/augmentation pipelines for AI model consumption
Stealth Ventures
Independent Software Engineer & Hacker
Sep 2023 – Sep 2025·Remote

Took time to focus on Penetration Testing / Offensive Security, Reverse Engineering, and AI Agents. Bootstrapped and scaled several technical projects.

  • Engineered a high-frequency ticket purchasing system (TypeScript) handling massive concurrency. Bypassed enterprise-grade anti-bot measures (Cloudflare, Akamai, QueueIT) headlessly. Scaled to $600K ARR
  • Built and managed profitable niche SaaS tools including Dineseat ($3K MRR) and Offermagnet
  • Fine-tuned Gemma/Llama models for NLP tasks and built data crawlers sourcing 32% of housing listings for a major aggregator
  • Architected AI dating app "DateToday" (Flutter, TS, FastAPI) using Grok/Gemini multimodal LLMs with 90% beta satisfaction
Wethenew
Founding Engineer & Engineering Lead
Jun 2019 – Sep 2023·Paris, France

Joined as the very first developer and helped scale the platform into one of Europe's largest e-commerce marketplaces (1M+ users, €100M+ GMV).

  • Architected core e-commerce backend (NestJS, MySQL, Redis, AWS) scaling to 500K+ orders/year & 350M+ API requests/month (99.99% uptime, ~70ms P95)
  • Designed, trained (PyTorch/Fastai on 500K+ dataset), & deployed predictive ML system automating 70% of inventory sourcing within 1 month
  • Resolved critical DB performance bottleneck via indexing, RDS read replicas & ElastiCache migration
  • Engineered CI/CD pipelines (GitHub Actions) & led migration to AWS (ECS, Lambda, EventBridge)
  • Helped build the tech team from 1 to 25+ engineers; led two agile squads focused on Supply Automation and Logistics
  • Led development of internal Flutter mobile apps for logistics & retail operations
Facebook (Meta)
1st Place Winner – Paris Hackathon
Jun 2019 – Jun 2019·Paris, France

Secured 1st place among top European engineering teams.

  • Led a team of 4 to build a real-time computer vision analysis tool
  • Recognized for speed of execution and algorithmic efficiency