Senior Backend Engineer
- Role
- Backend
- Experience
- Senior
- Employment
- Full-time
- Company size
- Startup
Open to AR, UY only. Set where you work from to check your eligibility.
No BS summary
Senior backend engineer with 5+ years, strong Node.js and NestJS/Express, REST APIs, and relational databases. Must be based in Argentina or Uruguay. Fintech/payments/credit experience is a plus.
Core skills
Required skills
Optional skills
Optional languages
This is a BNPL platform that pursues a mission to give Venezuelans back the opportunity to access credit.
Since our launch in 2022, we've been dedicated to promoting financial inclusion. Today we have more than 9 million active users, both consumers and merchants, and we've become a trusted brand in Venezuela, winning hearts and minds.
About the role
We're looking for a Senior Backend Engineer who owns systems, not just services. You'll design the backend that moves money for millions of people — which means correctness, resilience, and performance aren't nice-to-haves, they're the job.
You'll work close to Product and to other engineering teams, shaping how our platform scales as we grow. This is hands-on: you'll write code, make architectural calls, and be on the hook for how your services behave in production. The growth path here rewards engineers who go deep, raise the bar around them, and make the system better than they found it.
Overall you will...
- Design and build robust, scalable backend services in Node.js and NestJS (Express).
- Create and maintain high-performance RESTful APIs that other teams can build on with confidence.
- Build for financial correctness — idempotency, reconciliation, retries, and well-defined failure states.
- Model and manage relational data, primarily in PostgreSQL, with performance and integrity in mind.
- Make architectural and system-design decisions, and own the trade-offs behind them.
- Ensure optimal service performance and own production deployments end-to-end.
- Raise the engineering bar through code reviews, pairing, and clear technical standards.
- Mentor engineers and lead technical discussions, leaving the team stronger than you found it.
- Move fast across multiple workstreams in a dynamic, high-growth startup environment.
Qualifications
- Bachelor's degree in Computer Science or a related field, or equivalent practical experience.
- 5+ years of backend development experience, with solid depth in Node.js and NestJS (Express).
- Proven experience designing and operating RESTful APIs in production.
- Advanced knowledge of relational databases, preferably PostgreSQL.
- Experience writing unit and integration tests, and treating quality as part of delivery.
- Strong grasp of design principles and architectural patterns.
- Track record of shipping features independently and owning service performance in a fast-moving context.
- Ability to communicate complex technical concepts clearly, and to mentor others effectively.
- Excellent problem-solving and analytical thinking, with genuine curiosity about new technology.
Desirable skills
- Experience with cloud platforms, specifically Google Cloud Platform (GCP).
- Knowledge of containers and orchestration, such as Docker and Kubernetes.
- Experience with messaging and queuing systems like RabbitMQ, Kafka, or Pub/Sub.
- Experience building in fintech, payments, or credit.
- Spanish and English proficiency.
Interview Process
- Silver screening Interview
- Silver Technical Interview (System Design Interview)
- Client Screening Interview
- Client Technical interview
- Client Behavioral Interview
What you'll do
- Design and build robust, scalable backend services in Node.js and NestJS (Express).
- Create and maintain high-performance RESTful APIs that other teams can build on with confidence.
- Build for financial correctness, including idempotency, reconciliation, retries, and well-defined failure states.
- Model and manage relational data, primarily in PostgreSQL, with performance and integrity in mind.
- Make architectural and system-design decisions and own the trade-offs behind them.
- Ensure optimal service performance and own production deployments end-to-end.
- Raise the engineering bar through code reviews, pairing, and clear technical standards.
- Mentor engineers and lead technical discussions.
- Move fast across multiple workstreams in a dynamic, high-growth startup environment.
What they require
- Bachelor's degree in Computer Science or a related field, or equivalent practical experience.
- 5+ years of backend development experience, with solid depth in Node.js and NestJS (Express).
- Proven experience designing and operating RESTful APIs in production.
- Advanced knowledge of relational databases, preferably PostgreSQL.
- Experience writing unit and integration tests, and treating quality as part of delivery.
- Strong grasp of design principles and architectural patterns.
- Track record of shipping features independently and owning service performance in a fast-moving context.
- Ability to communicate complex technical concepts clearly, and to mentor others effectively.
- Excellent problem-solving and analytical thinking, with genuine curiosity about new technology.
- Preferred: Experience building in fintech, payments, or credit.
- Preferred: Spanish and English proficiency.
Benefits
- 100usd in app benefits
- Insurance Policy
- 15 PTO
Siena is the Agent of Record for consumer brands. One agent owns the entire customer journey, running on a shared intelligence layer. Consumer brands use Siena to collapse disconnected customer-management tools into a single agent across support, shopping, social, and operator workflows.