David K.

I build AI agents and Python backends that run in production. Matchi, the WhatsApp AI platform I built as co-founder and CTO, is used by 400+ paying real-estate brokers and handles 65,000+ WhatsApp messages a month. I cut its AI cost per chat turn by 87% at rollout. Hire me to ship a WhatsApp or voice agent, add LLM features to your product, fix a slow or expensive backend, or lead your tech as a fractional CTO. WHAT I BUILD - AI agents on WhatsApp and voice: multi-agent systems with 100+ tools, support agents that answer instead of a human, real-time phone agents (Twilio + Gemini Live) - LLM apps and automation: tool-calling workflows, structured outputs, evals, and MCP servers that connect ChatGPT and Claude to your product - RAG and matching: vector search with PostgreSQL + pgvector, embeddings, hybrid ranking - Generative image and video pipelines: virtual staging, branded creatives and listing videos, with quality checks and cost caps - Internal tools: one app that replaced Monday, a help desk, Grafana and a sales CRM for my team - Backend and infrastructure: Python (FastAPI, Django, Celery), PostgreSQL and pgvector, Redis, GCP and AWS, plus AI cost control (token ledgers, model routing, context trimming) - Fractional CTO: product and technical roadmap, architecture, hiring and mentoring engineers, stack decisions BACKGROUND 7 years of engineering. Backend Tech Lead at OurRitual, software engineer at Barclays Investment Bank, AI infrastructure at Sett. Google Cloud certified (Associate Cloud Engineer). GOOD FIT IF YOU NEED TO - Turn an AI idea into a working product fast - Add AI agents, chat or automation to an existing product or business - Fix an AI system that's slow, expensive or unreliable - Get senior technical leadership without a full-time CTO Languages: English, Czech, Russian, basic Hebrew. Based in Israel (GMT+3), with good overlap with EU and US East Coast hours. Send me a short description of what you're building, and I'll reply with how I'd approach it.