Hi, my name is

Omar Contreras

Backend Software Engineer

I build reliable, scalable systems that power real products. Focused on distributed systems, payment platforms, and AI agent architectures.

About Me

I'm a software engineer with experience building payment systems at scale, SaaS platforms, and AI-powered tools. At Twilio, I worked on payment processing infrastructure handling millions of transactions, earning a promotion to L2 Software Engineer.

My background spans distributed systems, API design, and full-stack development. More recently, I've been exploring AI agent architectures and building open-source tools for conversation parsing and knowledge orchestration.

Location
San Francisco, CA
Focus
Distributed Systems, Payment Platforms, AI Agents
Languages
Python, Java, Scala, TypeScript

Where I've Worked

2019 — 2023

Twilio

Software Engineer (L1 → L2)

  • Built and maintained payment processing systems handling millions of transactions
  • Promoted to L2 for impact on billing infrastructure and cross-team technical leadership
  • Worked across Scala, Java, and Python services in a distributed microservices architecture
  • Contributed to API design and developer experience for payment integrations

2024

Panoculum

Software Engineer (Contract)

  • Migrated mobile application from React Native to React for web platform
  • Full-stack development with modern JavaScript tooling

2017 — 2019

DjaoDjin

Software Engineer

  • Built sustainability compliance dashboards for PG&E using Django and Vue.js
  • Full-stack SaaS development with REST APIs and frontend components

2009 — 2016

UCSF / UC Berkeley

Research Software Developer

  • Developed clinical research tools for mental health screening and SMS-based patient monitoring
  • Built data collection and visualization platforms used in published research
  • Contributed to 5+ peer-reviewed publications in clinical informatics

Things I've Built

echomine

Multi-provider AI conversation parser on PyPI with 2K+ downloads. O(1) memory streaming for 1GB+ files, BM25 ranking with boolean search, and export to Markdown/JSON/CSV. Strict mypy, library-first.

Python BM25 Streaming Pydantic PyPI

cognivault

4-agent LangGraph pipeline (Refiner, Critic, Historian, Synthesis) with real LLM integration. WebSocket streaming, FastAPI service layer, hybrid PostgreSQL search, and 6-axis classification routing. 86% coverage.

Python LangGraph FastAPI WebSocket PostgreSQL

chronovista

Local-first YouTube analytics platform with 6K+ tests. React frontend, FastAPI backend, transcript search, deleted video recovery via Wayback Machine, and Google Takeout ingestion.

Python TypeScript React FastAPI PostgreSQL

Gmail Buddy

Gmail management with 96% faster bulk operations. Circuit breaker patterns, adaptive rate limiting, dual OAuth2/Bearer auth, and 85% test coverage.

Java Spring Boot Gmail API OAuth2

Twilio Payment Systems

professional

Payment processing infrastructure at Twilio handling millions of transactions. Billing APIs, subscription management, and revenue systems.

Scala Java Python Microservices Payments

Tech Stack

Languages

Python Java Scala TypeScript JavaScript SQL

Backend & APIs

Django Flask FastAPI Spring REST

Data & Storage

PostgreSQL Redis Kafka S3

Infrastructure

AWS Docker Kubernetes CI/CD Terraform

AI & Agents

LangGraph Pydantic AI Multi-Agent Systems Prompt Design

Practices

TDD Code Review System Design Agile