Filip Vavera

Professional summary

Senior full-stack and systems engineer with 12+ years shipping secure, high-performance web products in small teams. I own work from architecture through implementation, deployment, and production operations. My strongest work includes high-volume ClickHouse and SQL pipelines, a zero-downtime authentication migration, observability and incident-response tooling, payments, cryptographic protocols, and production LLM and agent integrations. I move between rapid prototypes and production systems with broad ownership and concise async collaboration.

Core strengths

End-to-end product delivery across architecture, backend, frontend, deployment, and production operations
High-volume data systems: ClickHouse, PostgreSQL, MySQL, Kafka, SQL optimization, workers, and analytics pipelines
Security beyond framework defaults: authentication, authorization, SSO, SAML, MFA, OAuth, and cryptography
AI-assisted engineering: production LLM integrations, agent workflows, orchestration, evaluation, and iteration
Observability and reliability: incident response, high availability, performance optimization, and safe migrations

Selected product and systems work

Signal - LLM-powered website editor for creating and manipulating content through natural-language interactions.
Noise Protocol - Elixir implementation of the Noise Protocol with explicit handshake state machines.
secp256k1 - High-performance Elixir NIF bindings in C for Bitcoin’s secp256k1 cryptography library.

Work experience

CrazyEgg - Senior Software Engineer

February 2022 - present

https://crazyegg.com/

Own technical design and production delivery of secure, horizontally scalable Elixir backend systems for a high-traffic analytics product, from architecture through rollout and operation.
Rewrote a 20-year-old custom Ruby authentication system in Elixir, adding SSO, SAML, MFA, and secure password flows while preserving full backward compatibility, zero downtime, and high availability.
Expanded a single compromise report into a production-wide investigation that identified 40 malicious A/B tests across 33 accounts, then shipped durable login auditing and trusted-device verification within 27 hours.
Built and optimized high-throughput data pipelines, SQL queries, and background workers processing millions of events per day on ClickHouse and MySQL.
Own observability and reliability using Datadog, Sentry, and Grafana; built tooling that improved Customer Success incident response by about 20 percent.
Ship production LLM and agent integrations, including workflow orchestration, evaluation, and iteration with Customer Success and engineering.

BnT - Software Architect

May 2020 - December 2020

https://bntlab.com/

Sole backend engineer in a three-person team, delivering the complete Event Sourcing and CQRS backend for a greenfield gold-trading product.
Implemented payments, FX conversion, and transaction workflows while owning data modeling, security, scalability, and reliability in close collaboration with mobile and design.

DivvyPay (now BILL Spend & Expense) - Team Leader and Senior Software Engineer

April 2018 - February 2022

https://www.bill.com/product/spend-and-expense

Joined during Divvy’s early startup stage, led a team of 8 while remaining hands-on, and operated as its first distributed engineer across time zones.
Owned technical strategy and implementation for payment processing, bank integrations, credit-card issuance, and loan systems handling concurrent, low-latency money movement.
Built and hardened services for critical payments, fraud-sensitive credit workflows, and compliance-constrained financial data.

profiq - QA Engineer to Fractional CTO

January 2015 - April 2018

https://profiq.com/

Progressed from QA automation to full-stack development and technical leadership, shipping React applications, Node.js services, real-time Django systems, IDE plugins, and early VR products.
Served as fractional CTO for multiple startups, owning technology strategy, architecture, implementation, and delivery in small teams.

Technical skills

Languages: Elixir, SQL, TypeScript/JavaScript, Python, Ruby (maintenance), C (production NIF bindings), C++ (first language, non-professional)
Web & frameworks: Phoenix, Phoenix LiveView, OTP, React, Django, Node.js, Tailwind
Data & infrastructure: ClickHouse, PostgreSQL, MySQL, Redis, Kafka, Docker, Kubernetes, AWS, Google Cloud
AI-assisted engineering: Coding-agent workflows, production LLM integrations, agent SDKs, orchestration, and evaluation
Observability & reliability: Datadog, PostHog, Sentry, Grafana, Prometheus, high availability, incident response
Security & architecture: Cryptography, authentication and authorization, MFA, OAuth, SAML, protocol design, Event Sourcing, CQRS