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Agent guide: [/agents.md](https://www.wearedevelopers.com/agents.md). --- # Tech Lead / Solution Architect - **Company:** Número De - **Location:** Barcelona, Spain (Remote available) - **Contract:** Permanent contract - **Skills:** Application Programming Interfaces (APIs), User Authentication, Automation of Tests, Cyber Security, Continuous Integration, Data Deduplication, Relational Databases, Distributed Systems, Monitoring of Systems, Intrusion Detection Systems, Python (Programming Language), Key Management, PostgreSQL, OpenID, RabbitMQ, Regression Testing, Prometheus, Single Sign-On, Systems Integration, Workflow Management Systems, Data Logging, Backend, Fastapi, Event Driven Architecture, Core Data, Apache Kafka, Dynatrace, Docker - **Published:** August 12, 2026 - **Apply:** https://www.adzuna.es/contact-us.html ## About the Role + Senior-level experience in backend engineering and solution architecture, with a proven track record of shipping production systems. + Strong understanding of distributed systems and failure modes, including retries, idempotency, consistency, race conditions, deduplication, and recovery strategies. + Hands-on experience designing and implementing backend services, ideally using Python and frameworks such as FastAPI. + Strong knowledge of relational databases, particularly PostgreSQL. + Experience with queues and event-driven architectures using technologies such as NATS, RabbitMQ, Kafka, or comparable platforms. + Strong understanding of APIs and integrations with external platforms and services. + Experience implementing OIDC, SSO, authentication, authorization, roles, permissions, and secrets management. + Practical knowledge of observability and monitoring technologies such as OpenTelemetry, Prometheus, ELK, or similar platforms. + Strong experience with integration, end-to-end, and regression testing, including integrating automated QA into CI pipelines. + Familiarity with Docker and modern software delivery practices. + Ability to independently make architecture decisions, define technical contracts, and translate ambiguous requirements into actionable solutions. + Strong analytical and problem-solving skills, with a proactive approach to identifying reliability, security, and scalability risks. + Excellent communication and collaboration skills, with the ability to explain technical decisions clearly to both technical and non-technical stakeholders. + Comfortable working autonomously in a project-based environment and taking ownership from architecture through implementation and delivery. ## Description This position is listed on behalf of a partner company, who manages all applications and next steps. Our partner is looking for a Tech Lead / Solution Architect - Backend, Workflow Engine, SSO, Observability, QA based in Spain. This is a senior technical leadership opportunity focused on designing and delivering the backend foundation of a new Legal OS MVP. You will own architecture decisions across backend services, workflow orchestration, security, observability, and quality engineering. The role combines hands-on engineering with solution architecture, requiring you to turn complex requirements into reliable, production-ready systems. You will design resilient workflows with strong guarantees around retries, idempotency, consistency, auditability, and failure recovery. You will also establish secure SSO and permissions models while building comprehensive observability and automated QA practices. The environment is highly autonomous, project-based, and focused on delivering a pragmatic MVP with a strong emphasis on reliability and security. This role is ideal for a senior backend engineer or architect who enjoys owning technical direction and building robust systems from the ground up. Accountabilities + Own backend architecture and technical direction, translating product goals into scalable and maintainable production solutions. + Define the architecture boundaries and minimal service contracts, including APIs and event-driven interfaces required for the MVP. + Design the core data model, including Matter IDs, mapping rules, and idempotency keys to ensure reliable and consistent processing. + Build and define the workflow layer with retry and backoff strategies, dead-letter handling, replay capabilities, deduplication, and resilient failure recovery. + Establish security architecture covering SSO, role-based permissions, access controls, and secure secrets management. + Implement comprehensive audit trails that clearly capture who performed an action, what occurred, when it happened, and why, supported by correlation IDs and distributed tracing. + Design and implement observability practices covering structured logging, metrics, tracing, system health, and operational troubleshooting. + Establish robust QA gates covering integration, end-to-end, and regression testing for critical workflows such as document delivery, deadlines, and audit functionality. + Collaborate with relevant stakeholders to make pragmatic architectural decisions and ensure solutions are ready for production. + Contribute hands-on code and technical implementation while maintaining a strong focus on reliability, security, maintainability, and operational excellence. ## Related Videos - [Inside Bitpanda's Tech Stack: Scaling a European Fintech Leader - Markus Dorner](https://www.wearedevelopers.com/videos/1979-inside-bitpanda-s-tech-stack-scaling-a-european-fintech-leader-markus-dorner) - [Intro to FastAPI](https://www.wearedevelopers.com/videos/462-intro-to-fastapi) - [Keeping applications secure by evolving OAuth 2.0 and OpenID Connect](https://www.wearedevelopers.com/videos/100152-keeping-applications-secure-by-evolving-oauth-2-0-and-openid-connect) - [Docker Compose: Rediscovered](https://www.wearedevelopers.com/videos/1978-docker-compose-rediscovered) - [Why make use of an integration platform in today's software developments and infrastructure?](https://www.wearedevelopers.com/videos/758-why-make-use-of-an-integration-platform-in-today-s-software-developments-and-infrastructure) - [Building and Deploying Multi-Agent Systems with ADK and Vertex AI](https://www.wearedevelopers.com/videos/1918-building-and-deploying-multi-agent-systems-with-adk-and-vertex-ai) ## Related Articles - [The 7 Most Popular Backend Frameworks for Developers](https://www.wearedevelopers.com/magazine/403-the-7-most-popular-backend-frameworks-for-developers) - [Why Upskilling And Reskilling is Important For Developers](https://www.wearedevelopers.com/magazine/428-why-upskilling-and-reskilling-is-important-for-developers) - [How We Built a Worry-Free System That Runs for 10+ Years – And What We’d Do Again](https://www.wearedevelopers.com/magazine/751-how-we-built-a-worry-free-system-that-runs-for-10-years-and-what-we-d-do-again) - [Fully Remote Software Engineer Jobs](https://www.wearedevelopers.com/magazine/447-fully-remote-software-engineer-jobs) - [Is Software Engineering Over-Saturated?](https://www.wearedevelopers.com/magazine/418-is-software-engineering-over-saturated) - [Top-Paying Tech Jobs (with Salaries)](https://www.wearedevelopers.com/magazine/372-top-paying-tech-jobs-with-salaries)