Bernardo Castro · available for senior roles

Voice AI Engineer.
agents that answer the phone_

Voice is agentic AI with no margin: 1 second to respond, interruption mid-sentence, and a caller who hangs up when it fails. I co-founded Pinecall and built the stack it runs on — media server, turn-taking, tool calls, SIP, WebRTC, WhatsApp, and native SDKs where the agent rings your phone as a real call.

senior full-time or consulting  ·  uruguay — spain  ·  english · español
voice · agents · retrieval · applied cryptography ··
01 The voice stack

Every layer between
hello and hang-up.

Pinecall is the platform I co-founded: I built the core and still own it — the SDK and the voice server — while my co-founder Gabriel runs the agents and the clients day to day. That split is deliberate: it keeps me deep in the engine, and available. I've built or shipped voice agents on every layer of the modern stack, on mine and on the others.

25+ providers · 5 channels · ≤1s first response · thousands of production calls
Transport

One session whether the call arrives from a phone, a browser, WhatsApp, or an intercom on a wall.

webrtc media servers · sip trunking · twilio · rtp
Turn-taking

Barge-in, endpointing, and the buffering that makes a greeting land the instant the audio track is ready.

silero vad · smartturn onnx · deepgram flux eager end-of-turn · soniox semantic endpointing
Speech & reasoning

Tool calls under a latency budget, streamed replies, hand-off to a human mid-call, and a knowledge base answering from real documents.

streaming tool calls · knowledge-base rag · hot-reload mid-call · skills loaded on demand · call log with cursors
Provider matrix

25+ STT, TTS and LLM providers behind one interface — swappable per agent, per phone number, at runtime.

soniox stt-rt · deepgram flux · elevenlabs + scribe · cartesia · gladia · openai realtime s2s · anthropic · google · mistral
Frameworks & platforms

I built one end to end — and ship on the others when they're the right call for the client.

pinecall (co-founded) · pipecat (daily) · twilio media streams · telnyx · jambonz (drachtio)
Clients

The agent is a real call on the lock screen, not a tab — native ringing like WhatsApp, answer before unlocking.

@pinecall/web widgets · @pinecall/ionic · react native · callkit native calls · electron desktop
Evaluation

Agents tested like software: a judge LLM converses with the agent against a spec — including real voice-mode calls, in CI.

deepeval · pinecall test --voice · judge llms · yaml agent specs
Multi-tenant from the first commit: one agent per customer, generated per tenant, isolated by construction.
02 Demos

Things you can open_

Ordered by how hard they are to fake. Every demo is mine — no client agents, no client flows.

★ hardest to fakewatch ▸

A voice agent that opens a physical door

A SIP intercom on a wall plus a desktop app: the agent answers, verifies the visitor, and fires the DTMF relay. Ships here in demo mode, no hardware attached.

agentFront desk. Who's visiting?
visitor — María, 15:00 with Ana.
⚙ visitors.lookup → match · badge #482
▸ DTMF #9 — door A open
sip intercom · dtmf relay · mjpeg feed · protocol stepper
ios · android react native ▸ ionic ▸

The agent rings your phone

A true native call — CallKit, system audio, answer from the lock screen. Not a WebView with a microphone.

Bernardo
incoming · via pinecall
callkit · system audio · @pinecall/ionic · react native
live agentstalk to them ▸

Real agents, real businesses

Not verticals — deployments. Pick one; each runs against a live system, right here in the browser.

Lucía
Lucía
LumiCRM · front desk
works a real spa's diary
Carolina
Carolina
KickboxingZF · enrolment
sells real memberships
Atlas
Atlas
Axion · market reporter
reads a quant data lake
Vera
Vera
your website & documents · RAG
talk with your website or PDF
same agent shape, different tenant — no forks
the product —everything above runs onpinecall.io· management api · dashboard · cli · typescript sdkopen ▸
03 Experience

18 years shipping.

Five with AI in production — as a team lead, a co-founder, and the engineer partners call for the hard ones.

May 2026 — now
AxionQuant Systems Engineer · with Cloudacio

Decision infrastructure for autonomous AI agents, deployed first against crypto-derivatives quant research — I designed and own the full stack: the agent control surface, the evidence layer, and the data platform underneath. Agents pre-register hypotheses over MCP before any outcome exists and a live forward clock adjudicates — a backtest can only reject, never promote — on append-only ledgers over an 843M-row lake. The durable asset is proprietary point-in-time data: purpose-built 24/7 collectors capturing what can't be bought or reconstructed after the fact, now enriched with ML-derived features at capture time and powering in-house strategy research — a thesis earned by first measuring public data to exhaustion. The multi-tenant control plane deploys each tenant's agents in isolated containers over that same infrastructure, each judged on its own forward clock.

python · clickhouse · fastapi · claude code · mcp · gcp
2025 — 2026
ServiceHubAI Engineer · via Cloudacio

Owned the year-2000 legacy PHP platform the business actually ran on — healthcare interpreting, 2.5M+ encounters/year — and migrated its highest-value features to the 5-person team building Aurora, its replacement. A multi-agent architecture made that tractable: MCP sync, a schema-aware database agent, and a retrieval engine, because finding the right code cost more context than any other step. Retrieval had to answer over more than source: internal documents, and the specific function buried in an 8,000-line file — which is why it grew custom indexing strategies per kind of file. That engine was brainbank, later rewritten as megabrain.

claude code · mcp · retrieval · php · sql server
2025 — 2026
Pinecall.ioCo-Foundersdk & server

Co-founded and built an all-in-one real-time voice AI platform (phone, WhatsApp, and web), processing thousands of production calls for clients including Naffco (fire safety, UAE), Cointel (Bilbao), TPX.security (Mexico), Relatyon (Madrid) and Cloudacio (New York). Owned the full stack — media server to TypeScript SDK — and still own the core today, while my co-founder Gabriel Cardama and his team run the agents and the accounts. The split is deliberate: it keeps me on the engine.

python · typescript · webrtc · twilio
2020 — 2025
DigitalBGASoftware Architect · AI Team Lead

Nearly five years at one of the fastest-growing life-insurance agencies in the US (3× Inc. 5000). A Twilio voice bot that recovered six figures in lost leads; a complete e-app system — 4,000+ e-apps with Mutual of Omaha and other carriers; and a call-center Conversation Analyzer — diarization up to 5 speakers, target-agent ID from a voice sample, Whisper large-v3, per-segment speech emotion.

ruby · php · react · python
2017 — 2019
CrisalixFull-Stack · Barcelona

3D medical imaging. Built the public API from scratch, an image editor with comparison tools, subscription manager and KPI dashboards. Won the first company hackathon (selfie → 3D model).

ruby · js
2008 — 2020
+ 8 earlier rolesfull-stack · US & EU clients · since age 17

CallAction (serverless migration), PUSHTech, Teamitup NY, Tarmac, Dawson — and Cubox, the Montevideo studio founded by an early Twitter engineer, where I learned TDD and pairing shipping for US startups. Plus flypluna.com, a CMS for a national airline, shipped at 18.

résumé (pdf) ↓
04 Skills

Six areas, real depth.

Every item below has shipped — no aspirational tags.

Autonomous agents
Claude Agent SDK · Claude Code (co-routines, hooks, custom skills, plugins, slash-commands, sub-agents, headless runs) · MCP servers & tools · Claude Code channels — research preview (MCP servers pushing CI results, webhooks & Telegram/Discord messages into a live session) · goals & self-paced loops · scheduled tasks & headless workers · shared task boards with atomic claims & expiring leases · multi-agent orchestration & fan-out · agent-operated infrastructure · guardrails, audit trails & pre-registration gates
RAG, retrieval & eval
Hybrid retrieval (dense + BM25 + RRF) · AST-aware chunking (cAST) · GraphRAG over import/call graphs · LLM rerank · adaptive single→multi-agent routing · flow/memory caching · embedding bakeoffs · DeepEval harnesses · judge-LLM agent specs · SWE-bench evals
Voice & speech ML
WebRTC media servers · SIP · Twilio · Telnyx · jambonz/drachtio · Pipecat (Daily) · Silero VAD · SmartTurn ONNX · Whisper large-v3 · speaker diarization · target-speaker ID · speech emotion analysis · barge-in & turn detection
Models & data
Ollama · vLLM · llama.cpp · QLoRA · SFT/DPO · AWQ/GPTQ quantization · ClickHouse · Postgres · Mongo · SQL Server · leak-free backtesting (purged cross-validation)
Frontend & mobile
React · Vite · Astro · design systems · React Native · Ionic · native iOS/Android call UX — system audio sessions, lock-screen controls · Playwright
Backend, applied crypto & shipping
Python · TypeScript · Ruby · PHP · FastAPI · Hono · Rails · SSE/WS · Ed25519 · XML-DSig · PAdES · OpenTimestamps · GCP · Cloud Run · AWS · CI with npm provenance
05 Open source

Tools I made public.

Infrastructure I built so agents work from ground truth, not guesses. github.com/bernatch22.

taskops pypi · mit
$ uv tool install taskops-cli

A shared work board for teams of coding agents running in parallel, with a human who decides. They stay out of each other's way by mechanism, not by prompt: one lease per card, one worktree each, a branch pinned to it for life. Append-only event log; main is written by a person.

python · zero runtime deps · mcp github ▸ pypi ▸
mypry npm · mit
$ npm i -g mypry

The interactive full-stack debugger for AI agents: pause, step and inspect live Node backend and browser frontend state in one session, over MCP. It replaces guessing with a breakpoint.

typescript · cdp · playwright demo ▸ github ▸ npm ▸
megabrain pypi · mit
$ pip install megabrain

The retrieval engine behind the ServiceHub migration: ask a codebase a question, get the exact source back. Hybrid dense + BM25 + RRF, AST-aware chunking, GraphRAG over import/call graphs — no LLM in the ranking path.

python · tree-sitter demo ▸ github ▸ pypi ▸
shipway npm · mit
$ npm i -g shipway

Deploy apps over SSH — no Docker, no cloud lock-in. Boring, reliable, and it has not paged me at 3am.

typescript · node 20+ · rsync github ▸ npm ▸
06 References

People I've worked with.

Reach out — they'll vouch.

"
I've known Bernardo since we were kids on the hackerss.com forum — two decades later he's still who I call when a problem is genuinely hard. He now builds the AI agents inside TPX.security — the real thing, not a demo.
Rafael Bucio
Rafael Bucio
Founder · TPX.security
"
Bernardo brought real AI into our operation — from real-time voice agents to helping on the harder AI and ML problems. Deep technical skill, ships end to end, and does it with total integrity.
Boni Lozano García
Boni Lozano García
VP Security & Loss Prevention · SBT · Partner, Relatyon
"
He's the kind of engineer you want on the hard ones — deep across the stack and into AI, with the discipline to take an idea all the way to something that actually ships.
Andres Bottan
Andres Bottan
SRE Project Leader · Mercado Libre
07 Contact

Let's ship
something real_

Open to senior AI engineering roles, high-agency contract work, and Claude Code / agentic system engagements. Fastest response is email; I read every message myself.

Book 30 minutes hello@bernardocastro.dev
github / bernatch22 linkedin x / twitter