Oscar Ospina

Lead · Senior Fullstack Developer · 13+ years

LinkedIn ↗

Experience

Where I've built things

SUMZFinancial Services Platform

Lead Senior Full Stack Developer

Oct 2024 — Present · 15 months

Team: 5 devs · 2 UX · 1 PO

High-volume financial services platform processing payments, loans, and account management for BNPL clients.

99.97%uptime

Architected cloud-native microservices platform on GCP serving 1,000+ customers, migrating Elixir/Phoenix to Node backend with PostgreSQL, deployed via Cloud Run with auto-scaling.

15+deploys/week

CI/CD pipeline on GitHub Actions + Cloud Build, Docker containerization, Terraform IaC — zero-downtime releases.

90%fewer incidents

Dropped from 10/month to <1/month via observability stack (Cloud Monitoring, Prometheus, structured logging). MTTR 4h → 45min.

45Klines decomposed

Led monolith → event-driven microservices (7 services: auth, payments, notifications, reporting, user-mgmt, loan-processing, audit). Feature deploy 2 weeks → 3 days.

40%faster reviews

Weekly architecture review sessions, code review standards, OpenAPI docs. Mentored 3 juniors → mid-level.

Node.jsTypeScriptPostgreSQLGCPCloud RunTerraformVitestDocker

TranquiFinancial Agent Platform

Lead Senior Full Stack Developer

Aug 2023 — Sep 2024 · 13 months

Team: IC in 12-person team

Platform for agents to manage customer accounts, transactions, and high-volume queries with strict performance requirements.

95%crashes eliminated

From 15 critical failures/week to <1/week. Heap profiling, circuit breakers, N+1 query fixes via TypeORM, rate limiting. Saved $45K/month.

45% → 95%test coverage

Jest (2,500+ cases), Supertest API tests, CI blocks PRs below 80%. Reduced production bugs 68% (25/mo → 8/mo).

<300msupdate latency

Real-time dashboard for 200+ concurrent agents with Socket.io + React/TypeScript + MUI, SSE fallback for legacy browsers.

85%faster queries

Zero-downtime DB migration on 15M+ records: blue-green, CONCURRENTLY indexes, monthly partitions, PITR. 12s → 1.8s.

SOC 2passed audit

OAuth 2.0/JWT, RBAC with 15 permission levels, API signing, PCI-DSS logging, Snyk. Zero security incidents.

Node.jsExpressTypeORMPostgreSQLReactSocket.ioJestMaterial-UI

Genius SportsReal-Time Sports Betting

Senior Full Stack Developer

Jun 2021 — Jun 2023 · 24 months

Team: Cross-functional · 8 engineers

Live sports widgets for NFL, NBA, Caesars, FanDuel. Sub-second latency, millions of concurrent users during peak events.

2.5M+concurrent users

NFL Sunday games. Event-driven microservices, React/TS frontend, Node APIs, GraphQL, WebSocket streaming, AWS Lambda odds calc. P99 380ms.

47%bundle size cut

920KB → 487KB gzipped. Code-splitting with React.lazy, dynamic imports, tree-shaking, progressive JPEGs, Akamai CDN. TTI 4.2s → 1.8s.

82%DB load reduction

12K → 2.2K queries/min. Redis Cluster with consistent hashing, cache-aside, warming, pub/sub invalidation. Handled 5x March Madness growth.

<650msend-to-end latency

AWS SQS 50K+ msg/sec, WebSocket pooling (100K+ concurrent/instance), DataLoader for N+1, React virtualization for 10K+ betting options.

3.8 → 4.6★app rating

React Native mobile perf: native modules, FlashList, 35MB → 18MB bundle, offline-first with SQLite. Crash rate -78%.

95%test coverage

Jest (4,500+ unit tests), Cypress E2E, JMeter load testing at 100K users. TDD. Bugs -71%, 30+ releases/month.

ReactTypeScriptGraphQLNode.jsAWS LambdaRedisWebSocketsReact Native

IntergrupoConsulting · EPM Utilities

Junior Dev → Solution Architect

Mar 2013 — Jun 2021 · 8 years 3 months

Promoted from Junior Developer to Solution Architect within 8 years. Led 15+ enterprise projects for EPM utilities company.

$2M+annual savings

Azure cloud migration and process automation across 15+ enterprise projects.

2.5M+utility customers

Architected microservices platform with .NET Core APIs, Azure Functions, SQL Server. Downtime 12h/mo → 2h/mo.

15+devs mentored

Established code review practices, technical design doc standards, weekly architecture workshops.

.NET CoreAzureSQL ServerAzure Functions

Technical Skills

The toolkit

Languages

TypeScriptJavaScriptC#Elixir

Frontend

ReactNext.jsRemixTailwindMUIPhoenixLit

Backend

Node.jsExpressNestJS.NET Core

Databases

PostgreSQLSQL ServerOracleMongoDBRedis

Cloud

GCPAWSAzure

DevOps

DockerKubernetesTerraformGitHub ActionsAzure DevOps

Observability

PrometheusGrafanaDataDogCloudWatch

Testing

VitestJestCypressJMeter

Messaging

Pub/SubAWS SQSRabbitMQ

APIs

RESTGraphQLWebSocketsSOAPWebhooks

Oscar Ospina.

Where I've built things

The toolkit