Raffael Choi

Full-stack Software Engineer · C++, TypeScript, Rust, Python

Vienna, Austria · office@raffaelchoi.com · +43 664 927 28 55· raffaelchoi.com · linkedin.com/in/raffaelchoi

Full-stack engineer who takes products from an empty repository to production: a custom C++ MMO client in Unreal Engine 5 and an AI voice agent running speech recognition, a language model and synthesis entirely on local hardware. Before that, four years as lead PvE developer on a game server that grew from 30 concurrent players to over 200,000 while every raid, dungeon and boss encounter on it came through me. Comfortable from a rendering loop to a deployment pipeline.

Selected work

Eternal Crossing - MMO client in Unreal Engine 5

2026 - present · C++, UE 5.8, Python
  • Wrote the network client by hand - socket layer, opcode parsing and building, streamed world entities - against a binary wire protocol, because an engine ships a renderer and a physics system but not an MMO.
  • Built the in-game interface in UMG - vendor, bank, auction house, spellbook, pet, auras, cast bar, loot - plus headless Python harnesses that exercise the protocol without launching the editor.

Frostcord - self-hosted communication platform

2025 - present · Frostforge fork of Sharkord (MIT) · frostcord.com
  • Lead developer on a Discord-class platform: end-to-end encrypted DMs, WebRTC voice and video, roles, permissions and moderation - four client targets from one monorepo, shipped as one binary bundling server and web client.
  • Wrote the licence server and the provisioning API that make it sellable: signed licence validation bound to a nonce and timestamp against replay, and one call that builds a hardened container, injects the licence, writes the proxy route and DNS, and waits on a health check.

Frostphone - self-hosted AI telephony

2025 - present · Frostforge · frostphone.com
  • Built a twelve-container stack that answers phone calls through LiveKit SIP: faster-whisper for speech recognition, Ollama for the language model, neural TTS for synthesis - all of it on local hardware, with no cloud version and no call audio leaving the machine.
  • Sized the model against the VRAM left after speech and synthesis take their share, and ruled out reasoning models because their thinking tokens arrive as audible silence on a phone line.

Experience

Founder & Software Engineer — Phonity Labs e.U.

January 2025 - October 2026 · Vienna, Austria
  • Built Frostphone, an AI voice agent that answers phone calls over SIP - speech recognition, LLM and synthesis, running entirely on local hardware.
  • Owned the whole stack: cloud PBX and SIP integration, inference services, the configuration dashboard, release gating, and the products shipped under the Frostforge label.

Software Developer — RISE - Research Industrial Systems Engineering

June 2025 - May 2026 · Vienna, Austria (remote)
  • Built internal tooling and integration logic in Ruby and Bash, and maintained Puppet configuration management across distributed infrastructure.
  • Coordinated deployments across datacenter server pools, resolved environment drift and made CI/CD behaviour predictable.

IT Operations & AI Project Lead — IT-Technik Klimt

December 2023 - May 2025 · Offenburg, Germany (hybrid)
  • Led AI project delivery for clients - scoping, implementation, post-deployment support - with cross-functional teams.
  • Replaced manual IT workflows with AI-driven automation, and ran critical server and network infrastructure: monitoring, incident management, backup strategy, compliance.

Lead PvE Developer — Turtle WoW

2019 - 2023 · Remote
  • Brought a discontinued server’s account and character databases to Turtle WoW in late 2019, turning down paid offers from competing projects so its players kept their characters. Concurrent players went from ~30 to over 1,000; the server later peaked above 200,000 concurrent across EU and CN.
  • Rebuilt the vanilla raid encounters the MaNGOS-lineage core had never implemented correctly - phase logic, timers, threat, add handling, ability rotations.
  • Shipped custom PvE content including Hateforge Quarry, a five-player dungeon with ten quests, and kept a heavily customised VMaNGOS fork cherry-pickable from upstream for four years.

Skills

Languages
TypeScript, Python, Rust, C++, PHP, Ruby, Bash, SQL, Kotlin, Lua
AI & ML
Local LLM inference (Ollama), speech recognition (Whisper), neural text to speech, tool and function calling, PyTorch, TorchScript, VRAM and latency budgeting, prompt and role design, n8n
Backend & real-time
Node.js, Bun, WebRTC, LiveKit, SIP telephony, Socket.IO, Next.js, React, Vue, Astro, Laravel, PostgreSQL, MySQL, SQLite, Redis, Drizzle
Infrastructure & security
Docker and Compose, Proxmox, KVM, Puppet, Linux (Ubuntu, Debian), CI/CD, Cloudflare Workers and Pages, Caddy, end-to-end encryption, SRP6, TOTP, Content Security Policy, ed25519 signing