Principal Full Stack Engineer Jobs in San Jose, CA

Role description

Fullstack Software Developer

Who We Are:

Born digital, UST transforms lives through the power of technology. We walk alongside our clients and partners, embedding innovation and agility into everything they do. We help them create transformative experiences and human-centered solutions for a better world.

UST is a mission-driven group of 29,000+ practical problem solvers and creative thinkers in more than 30 countries. Our entrepreneurial teams are empowered to innovate, act nimbly, and create a lasting and sustainable impact for our clients, their customers, and the communities in which we live.

With us, you’ll create a boundless impact that transforms your career—and the lives of people across the world.

Visit us at UST.com.

You Are:

UST is searching for a Fullstack Software Developer who will develop and maintain custom apps in VTEX IO and Store Themes; configure Checkout, Promotions, Master Data, OMS, Catalog, and Payments.

The opportunity:

• Build high-performing storefronts with React/TypeScript, optimizing Core Web Vitals, SSR, and caching. Integrate VTEX APIs (REST/GraphQL) and FastStore (preferred) using a headless commerce approach.

• Backend & Architecture: Design and implement microservices and REST/GraphQL APIs (Node.js/TypeScript), with ORM and relational databases (e.g., PostgreSQL/MySQL).

• Ensure security (OAuth2/JWT, rate limiting, input validation, secrets management) and observability (logs, metrics, traces). Document with OpenAPI/Swagger and maintain high quality with unit/integration testing (Jest; Cypress for end-to-end).

• Mobile - Flutter Design and develop Flutter apps with Clean Architecture, state management (BLoC/Cubit/Riverpod), modularization, and performance best practices (profiling, lazy loading, custom painters where applicable).

• Integrate mobile payment methods, push notifications, WebSockets/real-time, and Firebase (Auth, Firestore, Messaging) where applicable.

• Automate mobile CI/CD, code signing, and publishing/version management (enterprise or stores). Payments Integration with PSPs/gateways, tokenization/vault, 3DS, reconciliation, and reversal/retry flows.

• PCI compliance and controls (within the scope of the role), fraud prevention, and integration with anti-fraud/scoring systems. Design for high availability, resilience, and fault tolerance in critical payment flows.

• Collaboration & Leadership: Gathering requirements from business/finance/compliance and technical stakeholders. Mentoring mid/junior developers; end-to-end ownership from design to operation. Creating clear and maintainable technical documentation.

This position description identifies the responsibilities and tasks typically associated with the performance of the position. Other relevant essential functions may be required.

What you need:

• VTEX Ecosystem: Proven experience with VTEX: store configuration and customization, VTEX IO, custom app development, Checkout, Master Data, OMS, Catalog, and promotions. Integration with VTEX APIs (REST/GraphQL) and experience with Site Editor/CMS.

• Web Frontend: React + TypeScript + JavaScript (ES6+). HTML5/CSS3 (advanced proficiency), responsive/Mobile-First. Design patterns and accessibility; optimization of Core Web Vitals and SSR/caching.

• Backend: Node.js + TypeScript; design and development of REST/GraphQL APIs. ORM (e.g., TypeORM/Prisma/Sequelize) and relational databases (PostgreSQL/MySQL). Microservices, Clean Architecture, and SOLID principles.

• Security: OAuth2/JWT, rate limiting, validation, basic auditing. Swagger/OpenAPI for documentation.

• Quality & DevX: Unit testing (Jest) and end-to-end testing (Cypress preferred). Git (branching/PR/code review), CI/CD (GitHub Actions/Bitbucket Pipelines).

• Observability: structured logging, metrics, and traces (hands-on experience preferred). Mobile - Flutter Intermediate to advanced Flutter development: Clean Architecture, BLoC/Cubit/Riverpod, modularization, and performance best practices. Integration with payment platforms and Firebase (Auth/Firestore/Messaging) where applicable. Build automation and code signing (CI/CD mobile).

• Payments (domain) Extensive experience in e-commerce payments: payment orchestration, tokenization, 3DS, reconciliation, fraud prevention, retries, and error handling. Knowledge of PCI (within the developer's scope), security best practices, and payment compliance. Desired Skills FastStore in VTEX and advanced caching strategies.

• Docker and Kubernetes; cloud experience (AWS/GCP/Azure) for microservices. React Native (plus) and native iOS/Android modules. Complex integrations with ERP/OMS/CRM and messaging/streaming (pub/sub, events).

• Experience with advanced rate limiting, retries with backoff, and circuit breakers. Infra as Code (Terraform), feature flags, and toggling. Experience with high availability and SRE (basic SLO/SLI/SLAs).

Benefits

Employees receive eleven (11) paid holidays, two (2) weeks of paid vacation per year, and are eligible for health, dental, disability and life insurance.

What we believe:

We proudly embrace the values that have shaped UST since day one. We build our culture of Humility, Humanity, and Integrity. These values inspire us to nurture a people-first, human centric culture that fosters diversity, prioritizes sustainable solutions, and keeps our people and clients at the forefront of all decisions.

Humility:

We will listen, learn, be empathetic and help selflessly in our interactions with everyone.

Humanity:

Through business, we will better the lives of those less fortunate than ourselves.

Integrity:

We honor our commitments and act with responsibility in all our relationships.

An Equal Opportunity Workplace, Free of Discrimination and Harassment

At UST, we strive to provide a work environment free of discrimination and harassment. We are an equal opportunity employer and employment decisions are based on merit and business needs. Our Human Rights Policy further illustrates our stand on this. We are committed to following fair employment practices that provide equal opportunities to all employees. We do not discriminate or allow harassment on the basis of race, color, religion, disability, gender, national origin, sexual orientation, gender identity, gender expression, age, genetic information, military status, or any other legally protected status. At UST, we value diversity and believe that a diverse workplace builds a competitive advantage.

Un lugar de trabajo con igualdad de oportunidades y libre de discriminación y acoso

En UST, nos esforzamos por proporcionar un ambiente de trabajo libre de discriminación y acoso. Somos un empleador que ofrece igualdad de oportunidades y basa las decisiones de empleo en los méritos y las necesidades del negocio. Estamos comprometidos a seguir prácticas de empleo justas que brinden igualdad de oportunidades a todos los empleados. No discriminamos ni permitimos el acoso por motivos de raza, color, religión, discapacidad, género, origen nacional, orientación sexual, identidad de género, expresión de género, edad, información genética, estado militar o cualquier otro estado legalmente protegido. En UST, valoramos la diversidad y creemos que un lugar de trabajo diverso construye una ventaja competitiva.

UST reserves the right to periodically redefine your roles and responsibilities based on the requirements of the organization and/or your performance.

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Skills

software engineering,flutter development,payment domain,integration testing,relational database

About UST
UST is a global digital transformation solutions provider. For more than 20 years, UST has worked side by side with the world’s best companies to make a real impact through transformation. Powered by technology, inspired by people and led by purpose, UST partners with their clients from design to operation. With deep domain expertise and a future-proof philosophy, UST embeds innovation and agility into their clients’ organizations. With over 30,000 employees in 30 countries, UST builds for boundless impact—touching billions of lives in the process.