Senior Back End Engineer in London

Every business needs to know who they’re really working with whether it’s suppliers, investors, partners, or third parties. At Xapien, we’re reinventing how organisations do that, combining speed, scale and accuracy with cutting‑edge AI. Since 2018, we’ve grown from a deep‑tech startup to a global player in AI‑driven due diligence and risk intelligence. 2024 was a landmark year as we closed a $10M Series A, earned recognition in the Chartis RiskTech100® and Everest Group’s Leading 50™, and expanded our products, markets and customer base. 2025 was even bigger: With new regulations, rising compliance pressure and growing reputation risks, organisations everywhere are demanding smarter, faster ways to work and they’re turning to us. Customers worldwide from global law firms and private banks to universities and nonprofits rely on Xapien to turn days of manual research into trusted insights, delivered in minutes. Customers in a diverse range of industries, with particular growth in wealth management, financial services and supply chain onboarding. Demand accelerating beyond our UK headquarters, across multiple continents with new customers in the Middle East, Asia, and Oceania.

Why this is an exciting time to join: This isn’t just another job role; it’s an opportunity to shape the future of the due diligence industry with a market‑leading product trusted by global organisations. Whether you’re in marketing, communications, sales, or finance, you’ll play a critical role in driving growth, building credibility, and defining how we connect our product to a rapidly evolving market. We’re scaling fast with more customers, more releases, and bigger regulatory and market challenges. Expectations are rising, due diligence now means real‑time insight, delivered efficiently and with impact. You won’t just be executing campaigns, closing deals, or managing numbers, you’ll be influencing strategy, optimising processes, and helping position a brand that’s setting the new standard for trust and transparency. For people who love learning, innovating, and making an impact that matters now is the moment to be a part of Xapien.

The Role: We’re hiring a Staff Backend Engineer to join our engineering team in a high‑impact technical leadership role. You'll work on our most challenging technical problems, own parts of our platform’s architecture, and help shape the technical direction of our backend stack. Our tech stack centers on Go microservices, with Temporal workflows, MongoDB and ElasticSearch running on Kubernetes in GCP. You'll work with modern patterns including event‑driven architectures, gRPC and REST APIs, and comprehensive observability with Grafana Cloud. You’ll take technical ownership of major domains within our platform — whether that’s our Investigations pipeline (web scraping, data provider integrations, LLM‑powered analysis) or our Core App systems (user journeys, features, and configuration). You'll be a technical authority, establishing patterns that others follow and driving initiatives that span multiple teams.

What You’ll Do:

• Own the technical direction and architecture for parts of our platform
• Design and build complex backend services and systems that scale
• Drive technical decisions that affect multiple teams
• Establish patterns, standards, and best practices that others will follow
• Lead complex technical initiatives from design through implementation
• Identify and address systemic technical challenges across our backend
• Write exemplary Go code that sets the standard for quality and design
• Mentor engineers across the organization, raising the technical bar
• Balance technical excellence with pragmatic delivery
• Influence technology choices and architectural direction
• Collaborate with engineering leadership on technical strategy
• Build new systems and features while improving our existing architecture

What We’re Looking For:

• 10+ years of professional software engineering experience
• Deep expertise in Go, with mastery of concurrency, performance optimization, and advanced patterns
• Proven track record of designing and owning large‑scale systems
• Strong experience with distributed systems, event‑driven architectures, or similar complex systems
• Deep understanding of databases, particularly MongoDB or similar NoSQL systems
• Extensive experience with microservices architecture and inter‑service communication
• Expert‑level understanding of containerization (Docker) and orchestration (Kubernetes)
• Experience establishing technical standards and patterns across teams
• Strong architectural thinking with ability to balance trade‑offs
• Track record of mentoring and developing other engineers
• Ability to drive technical initiatives with minimal guidance
• Experience influencing technical direction at an organizational level
• Excellent communication skills with ability to articulate complex technical concepts

Highly Desirable:

• Experience with Temporal or similar workflow orchestration systems at scale
• Deep knowledge of event streaming platforms like Kafka
• Experience with LLMs and AI integration (particularly for Investigations team)
• Background in SaaS platforms or B2B products at scale
• Expert‑level knowledge of observability tools (Grafana, Prometheus, etc.)
• Deep understanding of authorization patterns, security, and multi‑tenancy
• Experience with protobuf and gRPC

What Success Looks Like: In your first 6 months, you will have:

• Owned and driven a significant technical initiative to completion
• Established new patterns or improved existing ones across teams
• Mentored multiple engineers, visibly raising technical standards
• Contributed to architectural decisions
• Been recognized as a technical authority in your domain
• Made measurable improvements to system reliability, performance, or scalability
• Influenced the technical direction of our backend platform

Here’s our promise to you: We are going to work with you - to build a rewarding and fulfilling career with the opportunities, challenges and resources you need to do your best work. We succeed together‑ you will own a meaningful part of the business through our employee shares & equity programme. Private health insurance to keep you in tip‑top condition. Life Insurance – let’s hope nobody ever needs this! Unlimited holidays – yes, it really is uncapped – take the time you need, when you need it. Everyone is learning, developing and challenging themselves so we have a £1k professional development fund per year if you want to learn new skills, even new things outside of work. Most importantly of all, we will work with you, to help you realise your fullest potential, always.