Senior Software Engineer, Barcelona

Senior Software Engineer

Please note that we re a US-based company, so this position will be under a contractor agreement.

We re hiring a Senior Software Engineer with a strong backend focus who can still navigate the full stack when needed. You ll own core services (pricing, data ingestion, auth/permissions), shape our architecture, and partner with the founders on roadmap and trade-offs. This role is ideal for a self-starter who enjoys moving from design code production and can lead by example.

Beyond coding, you ll drive engineering initiatives, collaborate with co-founders, product and data teams, and support other developers. You ll ensure our application remains performant and scalable as we handle large data sets, complex filtering logic, and real-time updates for customers.

What You ll Do

1. Backend Platform

Design and implement services in (TypeScript) running on GCP (Cloud Run, Cloud SQL/Postgres, Pub/Sub, Cloud Storage, VPC).

Build and evolve multi-tenant SaaS primitives: RBAC, org/workspace models, JWT/OAuth auth flows, API keys, rate-limiting.

Ship reliable REST (and/or GraphQL) APIs with versioning, pagination, idempotency, and strong contracts.

Build background workers schedulers for pricing jobs, data ingestion, and sync tasks (Pub/Sub/queues, cron).

Performance engineering: caching strategies (e.g., Redis), query optimization, profiling, hot-path tuning.

Observability: metrics, tracing, structured logs (OpenTelemetry, Cloud Logging/Monitoring, Sentry).

Secure by default: least-privilege IAM, secrets management, encryption in transit/at rest, audit trails, PII handling, SOC2-friendly habits.

1. Data Integrations

Integrate with OTA/partner APIs design resilient adapters, retries, backoff, and data quality checks.

Model data for analytics workloads collaborate with data science on the pricing engine and evaluation loops.

1. Architecture Leadership

Co-drive the roadmap and architecture decisions (domain boundaries, service decomposition, buy vs build).

Set engineering standards, review PRs, mentor teammates, and unblock delivery.

Balance velocity with reliability, cost, and long-term maintainability

1. Performance and Scalability

Optimize data-fetching flows and caching strategies to minimize latency and network overhead.

Identify bottlenecks in frontend or backend, propose architectural improvements, and ensure smooth scaling under high traffic.

Collaborate with DevOps/Infrastructure teams for CI/CD, monitoring, and alerting setups potentially work with Google Cloud, AWS, or Vercel.

1. Team Leadership Collaboration

Lead engineering initiatives work with the CTO and other senior engineers to define technical direction

Mentor other developers, conduct code reviews, and promote best practices in clean, testable code.

Break down product requirements or complex technical tasks into achievable sprints, providing accurate estimates.

1. Frontend touchpoints (as needed)

Contribute to endpoints/components when integration or contract changes require it.

Requirements

6+ years building production software at least 3+ years leading/owning backend services.

Expert in and a framework such as NestJS strong SQL and Postgres fundamentals

Hands-on GCP experience (or AWS/Azure with willingness to adopt GCP).

Proven SaaS chops: RBAC, JWT/OAuth, API design, multi-tenancy, background jobs, rate limiting, feature flags, A/B testing.

Security reliability mindset: secrets management, least-privilege IAM, auditability, SLO/SLI thinking.

Comfortable with CI/CD, Docker, and production debugging/observability.

Clear communicator (B2/C1 ENG) who enjoys owning problems end-to-end and participating in roadmap/architecture.

Why Join Walkway

Shape the Future of Travel: Influence architecture decisions on a high-impact, AI-driven SaaS platform (we recently won an Award)

Collaborative Culture: Work in a supportive, innovative environment that values continuous learning and open communication

NodeJS, GCP, typeScript, NestJS, AWS, SQL, Postgres, Backend, Software