Oniel Santos
Résumé
Oniel SantosSenior Full-Stack Engineer
Open to new roles · Remote

I build scalable products, APIs, and web experiences that feel finished.

6+ years shipping SaaS end to end — from PostgreSQL schemas and NestJS services to the React interfaces people use every day, and lately the AI integrations that automate the work behind them. I own products from first sketch to production.

View selected workGet in touch
Daily stack
  • TypeScript
  • React
  • Next.js
  • Node.js
  • NestJS
  • PostgreSQL
  • AWS
Selected work

Products I've architected, built and shipped.

Each one owned end to end — data model, API, interface and deployment.

HealthTech · SaaS

Medical appointment & queue platform

Clinics run on paper lists and guesswork. This platform turns scheduled appointments, walk-ins and doctor availability into one live queue that patients can follow from their phone.

Problem
Unpredictable waiting rooms and manual check-in.
My role
Architecture, API and web app — end to end.
  • Dynamic queue that re-estimates wait times on every check-in
  • Doctor schedules, shifts and appointment slots
  • Patient check-in with real-time status updates
  • NestJS
  • PostgreSQL
  • Next.js
  • WebSockets
  • AWS
LegalTech

Dominican legislation search engine

Full-text search across Dominican law with versioned documents, article-level links and relationships between laws, regulations and jurisprudence.

  • Versioned legal documents
  • Deep links to individual articles
  • Regulation ↔ jurisprudence graph
  • PostgreSQL
  • Full-text search
  • Node.js
  • Next.js
Public API

Dominican Republic geographic API

A clean REST API for provinces, municipalities and districts, backed by PostGIS so any coordinate can be resolved to its administrative area.

  • Hierarchical administrative data
  • Point-in-polygon lookups
  • Documented, versioned endpoints
  • PostGIS
  • PostgreSQL
  • NestJS
  • OpenAPI

Also shipped in production

  • Thryv

    AI workflow automation

    Claude AI integrated into internal support and operations workflows, reducing manual workload by 40%.

    Claude · Node.js · NestJS
  • Vertrical

    Multi-tenant microservices platform

    Kafka-connected services for digital-health clients; processing time dropped from 15s to under 1s.

    NestJS · Kafka · AWS
  • Intellisys

    National vaccination records API

    Records and appointments for 10M+ citizens; Elasticsearch cut search from 10s to sub-millisecond.

    NestJS · Elasticsearch
Capabilities

One engineer across the whole stack.

I'm most useful where product, backend and interface meet — turning a rough idea into something reliable people want to use.

  • 01

    SaaS product engineering

    Multi-tenant products taken from a blank repo to paying users — auth, billing, roles and the unglamorous parts that make them hold up.

    Next.js · NestJS · Stripe

  • 02

    Backend architecture

    Services, queues and data models designed to stay simple as traffic and teams grow. Microservices only when they earn it.

    Node.js · Kafka · Redis

  • 03

    API design

    Predictable, versioned REST APIs with clear contracts and documentation other teams actually enjoy integrating with.

    REST · OpenAPI · GraphQL

  • 04

    Frontend & interfaces

    Landing pages and product UI built with semantic HTML, modern CSS and restrained motion — responsive, accessible and fast.

    React · TypeScript · CSS

  • 05

    Data & search

    Relational schemas, geospatial queries and search indexes tuned for the questions the product needs to answer.

    PostgreSQL · PostGIS · Elasticsearch

  • 06

    Cloud & delivery

    Containerised deployments, CI pipelines and AWS infrastructure that make shipping small changes routine.

    AWS · Docker · GitHub Actions

Experience

Six years, three teams, real users.

Remote with product teams in the US and the Dominican Republic, across healthcare, government and small-business software.

Full résumé (PDF)
  1. Dec 2024 — Now

    Senior Software Engineer at Thryv

    All-in-one platform for small businesses · USA, remote

    • Integrated Claude AI into internal workflows to automate support and operational tasks, reducing manual workload by 40%.
    • Built the subscription management system with Node.js and NestJS that processes refunds across 6 countries, integrated with third-party billing services.
  2. Jan 2023 — Nov 2024

    Software Engineer at Vertrical

    Scalable, compliant software for digital-health companies · USA, remote

    • Built a multi-tenant microservices platform with NestJS and Kafka, cutting processing time from 15s to under 1s.
    • Created the Next.js micro-frontend infrastructure used to assemble products for 10,000+ customers.
  3. Apr 2020 — Dec 2022

    Software Developer at Intellisys D. Corp.

    Custom web, mobile and enterprise software · Dominican Republic

    • Built a secure NestJS API for a national vaccination system managing records and appointments for 10M+ citizens.
    • Indexed citizen records with Elasticsearch, bringing search time from 10 seconds to under 500µs.
Kind words

From people I've built with.

Oniel is a brilliant software developer who really understands how to build both people and products. His biggest strength is his ability to understand and analyze requirements and how he can connect with the rest of the team members. Even on the most difficult task, Oniel proved to be able to truly understand them and prioritize them correctly.

Stacey DíazSoftware Project Manager

Oniel has extensive experience in both web and AR/VR technologies that make him a very competent developer. In general, he is a great software engineer with a great deal of knowledge in front-end and back-end development. He is constantly learning and does not stop when faced with a problem, he is conscious and persevering. It's always fun and very productive to work with.

Leobardo NúñezSoftware Engineer

As a student at Cincinnatus, Oniel made a lasting impression due to his technical abilities, his enthusiasm for learning and being better, and his earnest desire to help other members of our community be better as well. When he wasn't making strides towards completing the program (to which he was also very committed), he would routinely be found helping others along. Even after graduating, we have continued to rely on him for support, and I have always appreciated his eagerness to continue mentoring those students who have come after him.

María Cruz MinayaCommunity Team Member, Cincinnatus
Contact

Let's build something useful.

Open to senior full-stack and frontend-focused roles, remote. Email is the fastest way to reach me.

Dominican Republic · UTC−4 · Working remotely with US teams since 2023