Description

Soy desarrollador mobile senior con más de 13 años de experiencia construyendo aplicaciones

iOS y Android, con especialización en React Native desde sus primeras versiones. He trabajado

para empresas en EEUU, Serbia y España, entregando apps en producción para sectores como

salud, fintech, lectura digital y transporte.

Actualmente trabajo como Mobile Developer en HTEC Group (Palo Alto, California), donde

desarrollo soluciones en React Native con TypeScript, Redux, Tanstack Query, Reanimated y

Firebase, entre otros. Mis apps están publicadas en App Store, Google Play y AppGallery.

Más allá del código, soy Scrum Master y Product Owner certificado por Scrum.org — lo que

me permite colaborar directamente con equipos de producto, entender el negocio y tomar

decisiones técnicas con criterio. Mi inglés está certificado con IELTS C1 (Overall 7.0), lo

que me permite trabajar sin fricciones con equipos internacionales.

Tengo además experiencia en trading algorítmico: diseño y automatizo estrategias de trading,

lo que me ha dado una perspectiva muy concreta sobre el desarrollo de herramientas para

mercados financieros (he trabajado con plataformas como NinjaTrader, entre otras). Es un

nicho interesante si buscas un desarrollador que entienda tanto el código como la lógica del mercado.

Trabajo bien en autonomía pero doy lo mejor de mí colaborando con equipos pequeños y

orientados a producto. Si buscas a alguien que no solo entregue código sino que entienda lo

que estás construyendo, aquí estoy.

More info: osiellima.com

Tech blog: osiel.hashnode.dev

Industry field of expertise

Languages

Spanish
Native or bilingual
English
Fluent

Workplace preferences

Remote only

Primarily works remotely

HTEC Group
Mobile Developer
HEALTH AND WELLNESS
June 2022 - Today (4 years)
Palo Alto, CA, USA
Senior Mobile Engineer @ HTEC Group (Palo Alto, CA) — building production-grade React Native applications for US and UK enterprise clients in TypeScript.

Current project — Digital Health Platform (NHS Innovation Accelerator)

The platform enables an NHS-equivalent Healthy Heart Check in under 10 minutes from a smartphone — measuring a 5-marker cholesterol panel, BMI, blood pressure and 10-year cardiovascular risk (QRISK3).

Frontend lead: 2 React Native apps (consumer + Pro for healthcare professionals)
2 internal npm packages and 1 web app
Backed by leading UK VCs (£2.5M)

Previous projects
Connected Worker platform for industrial manufacturing — digital work instructions, real-time collaboration, IoT/ERP/MES integrations, offline capability. Active in pharma, automotive, oil & gas and aerospace
Social content discovery platform for movies, TV, music and podcasts (iOS) — 100M+ titles, backed by executives from major US entertainment companies

Key contributions across all projects
Complex UI animations with Reanimated 2/3
State management with Redux and Easy Peasy
Server-state synchronization with TanStack Query
CI/CD pipelines with Bitrise for iOS and Android
Mentoring 2 junior React Native engineers
Technical interviewer for React Native engineering candidates as part of HTEC's hiring panel
React Native React Firebase Bitrise Jira/Confluence
Paycor
Senior Frontend Developer + Scrum Master
HUMAN RESOURCES
September 2020 - June 2022 (1 year and 9 months)
Belgrade, Serbia
Paycor is a US-based HR software company (NASDAQ: PYCR) with over
30 years serving SMBs across the US. I held a dual role as Senior
Frontend Developer and Scrum Master for a cross-functional product
team, working across web and native mobile platforms.

Key contributions:
Maintained and evolved a native clock-in app for Android (Java + Kotlin) and iOS (Swift), heavily used on tablets and iPads — featuring shift management, schedule tracking, and facial recognition for employee authentication
Led development of React and CSS implementations of core Paycor HR modules, replacing a legacy Silverlight/XAML desktop codebase
Built a comprehensive test suite with Jest and redux-saga, establishing a test plan strategy that prevented regressions throughout the migration
Introduced E2E testing with WebDriverIO to validate critical user flows end-to-end
Promoted to Scrum Master mid-engagement — ran sprints, retrospectives, and stakeholder ceremonies while maintaining full development output
Earned PSM I and PSPO I certifications (Scrum.org) during this role
React.js Swift Android Scrum App Store
Marvintech d.o.o
Senior Frontend Developer • · Project Manager
VIDEO GAMES AND ANIMATION
May 2019 - August 2020 (1 year and 3 months)
Belgrade, Serbia
Marvintech d.o.o was a Belgrade-based studio developing slot machine
games for the online European gaming market and for land-based
devices (arcade cabinets and gaming terminals).

Key contributions:

- Developed 6 production slot machine games (Roxy Bar, Arcadia, Jewellery, MadFox, Beba Monster, Hector) using JavaScript and PixiJS — covering game logic, reel mechanics, animations, and asset optimization for web and hardware delivery
Adapted the same game engine for both online and land-based platforms, handling different display and hardware constraints
Promoted to Project Manager — led a small cross-functional team (graphics + development) through the full game lifecycle, from design to production release
First hands-on experience leading people and applying Scrum/Agile methodologies, later formalized with PSM I and PSPO I certifications
Built and maintained the company's corporate website
JavaScript Pixi.js WebGL Scrum Project Management