Backend Engineer - Platform Core

Backend Engineer (Golang) – Platform Core

Location: Remote, European time zones, Full-time, Permanent

About FullEnrich:

Every go-to-market motion runs on data, but no single provider has ever had complete coverage. We solve that problem with waterfall enrichment: instead of relying on a single data source, we orchestrate 20+ premium providers around the world, automatically querying them until we find the best available contact information. The result is industry-leading coverage and data quality, helping sales and GTM teams connect with the right people faster.

What started as a better way to find emails and phone numbers has grown into a broader vision: becoming the trusted B2B data layer powering modern revenue teams and AI-driven workflows alike. Today, more than 5,000 customers, including companies like AWS, Deel, HubSpot, Clay, and Artisan, trust us to power their prospecting and enrichment.

Founded in Paris and now headquartered in San Francisco, we're a team of 50+ people across the US, Europe, LATAM, and Israel, growing quickly and building with speed, ownership, and ambition. That's where you come in.

About the Role:

At the heart of FullEnrich is our waterfall engine. It's the system responsible for deciding which data providers to call, in what order, under which conditions, and what happens when something fails. It works well today, but what we're building next is significantly more ambitious.

We're evolving the engine to become far more flexible and configurable, supporting account-specific requirements, dynamic routing based on different optimization goals, and seamless integration of new providers and behaviors without introducing unnecessary complexity.

This is a foundational part of our product, and getting the architecture right is critical to how we scale.

We're looking for an experienced Backend Engineer who enjoys solving complex infrastructure challenges and taking ownership of the systems behind them.

If you've built high-throughput routing systems, designed multi-provider orchestration layers, or worked on infrastructure that needs to adapt to different customers and use cases, this is exactly the kind of challenge you'll be taking on.

What You'll Do:

• Own and evolve our core routing engine: Take ownership of provider selection, fallback logic, load balancing, and queue management. Our waterfall currently operates as a modular Go monolith, and you'll help evolve it to support account-level customization at scale without introducing unnecessary complexity.

• Build and improve provider integrations: Design how we connect to and manage third-party data providers, focusing on rate limiting, reliability, and observability. This includes supporting external provider credentials, configurable provider ordering, and well-defined fallback behavior when providers are unavailable.

• Develop intelligent routing capabilities: Build the logic that dynamically selects providers based on different optimization objectives, including speed, coverage, compliance, and intelligent load balancing, while managing rate limits effectively.

• Design scalable multi-tenant architecture: Develop the foundations for sub-accounts, customer-specific credit pools, and endpoint-level configuration, ensuring the engine remains flexible, scalable, and maintainable.

• Build composable verification workflows: Integrate validity and compliance checks into the enrichment pipeline as configurable steps, allowing results to be independently verified regardless of their original data source.

• Strengthen our core architecture: Improve and refactor existing systems as we scale, applying strong engineering practices to keep our codebase clean, understandable, reliable, and easy to maintain.

• Shape technical decisions: Work closely with our engineering leadership to translate product requirements into thoughtful architectural solutions, balancing immediate needs with long-term scalability.

What Success Looks Like

In your first 3 months:

• Develop a deep understanding of our existing waterfall engine, provider integrations, and core backend architecture.

• Build strong relationships with the engineering team and identify opportunities to improve reliability, performance, and maintainability.

• Start contributing to the evolution of our routing engine, taking ownership of initial architectural improvements and technical decisions.

By 6 months:

• Take ownership of key components of our core platform, delivering meaningful improvements to provider orchestration, fallback logic, and routing capabilities.

• Help introduce more flexible, account-level configuration while keeping the architecture clean, scalable, and maintainable.

• Improve the reliability and observability of our provider integrations, reducing operational complexity as we scale.

By 12 months:

• Play a leading role in delivering a more intelligent, configurable waterfall engine that supports different customer needs and optimization goals at scale.

• Establish robust architectural foundations for multi-tenancy, composable verification, and continued provider expansion.

• Be a trusted technical contributor within the engineering team, helping shape long-term architectural decisions and ensuring our core platform remains reliable, performant, and ready for future growth.

What We're Looking For:

• Strong backend engineering experience: You've built and maintained production systems involving routing, fallback mechanisms, queues, concurrency, and rate limiting. You understand how distributed and multi-provider systems behave under pressure and how to design for reliability.

• An architecture-first mindset: You're comfortable taking a product requirement, identifying potential structural challenges, and designing solutions that will stand the test of time. You think beyond implementation and consider scalability, maintainability, and long-term impact.

• Deep experience with Golang: Go is at the core of our backend. You're confident working with modular architectures, clean code principles, and ideally hexagonal architecture.

• Experience managing technical complexity: You can navigate systems with multiple interconnected components, from account-level configuration and provider orchestration to compliance workflows and multi-tenancy, without compromising clarity or simplicity.

• Strong ownership and problem-solving skills: You're proactive, pragmatic, and comfortable making technical decisions. You enjoy getting into the details, understanding why systems behave the way they do, and finding solutions to challenging engineering problems.

• A collaborative approach: You communicate clearly, challenge ideas constructively, and enjoy working with other engineers to build reliable, high-quality systems.

Nice to Have

• Experience with data routing, enrichment pipelines, or multi-provider orchestration systems.

• Experience building API marketplace infrastructure or multi-tenant SaaS backends.

• Familiarity with API-first product architectures.

• An interest in the evolving data infrastructure landscape.

Our Tech Stack

Our backend is built primarily in Golang, following a modular, hexagonal architecture.

Our wider stack includes:

• Backend: Go (Golang)

• Databases & Search: PostgreSQL, OpenSearch

• Infrastructure: DigitalOcean, Docker

• CI/CD: GitHub Actions

• Monitoring & Observability: Grafana

You'll be joining an engineering team of around 10 people, working on one of the most critical components of our platform.

Interview Process

We aim to keep our process straightforward, transparent, and focused on getting to know each other.

1. Introduction to FullEnrich with our Talent team (30 min) – A chance to learn more about you, introduce FullEnrich and the role, and explore whether there's a mutual fit.

2. CTO & VP Engineering Interview (60 minutes): A conversation about your experience, the role, and a technical discussion based on a real experiment.

3. Technical Assessment: A take-home exercise completed in your own time, followed by a review and discussion.

4. Team & Culture Interview: Meet with a member of the team to learn more about how we work together and ensure there's a strong mutual fit.

FullEnrich is an Equal Opportunity Employer. All qualified applicants will receive consideration for employment without regard to race, sex, color, religion, national origin, protected veteran status, gender identity, sexual orientation, or disability.