Principal Backend Engineer

Heron processes millions of sensitive financial documents for some of the fastest-growing MCA Funders, Brokers, Insurers, and Fintechs in the US and UK. We're at a point where the volume, velocity, and complexity of the data flowing through our systems and is outgrowing the way they were originally built. We need someone who's done this before: taken a platform that works and made it scale. The Challenge We've built a document automation and workflow orchestration platform that lenders, funders and fintechs rely on to make real decisions. It's working, customers love it, and we're onboarding new ones faster than ever. The challenge is that our backend was built for speed-to-market, and now we need to make it built for scale. Concretely, that means: Abstractions that let us move fast : The backend systems and patterns that let a 15-person engineering team ship product confidently without breaking things for existing customers. Multi-tenancy at scale : Dozens of enterprise customers sharing the same cloud infrastructure, each with different data sensitivity requirements, SLAs, and integration patterns. Data volume and velocity : High-throughput processing of financial documents (bank statements, tax returns, pay stubs) with ML pipelines that need to be fast, accurate, and reliable. Security and compliance : Sensitive financial data handled to exacting standards. We’re excited about this challenge because it is the kind of problem that shows up when things are going well! We're hiring this role because we couldn’t be more confident in our trajectory but need to build the foundations for the next 10x. What You'll Own This is a hands-on, high-autonomy IC role. You'll work directly with our CTO (Dom) and Head of Engineering (Oli), and you'll have real ownership over the systems that matter most. In your first few months, you'll likely: Assess our current backend architecture and identify the highest-leverage areas for improvement around reliability, scalability, and security. Partner with the platform and infrastructure team to design and implement the core abstractions (data model, data pipeline reliability, deployment patterns) that will support our next phase of growth. Set the technical direction for how we scale our infrastructure from handling hundreds of customers to thousands, and from millions of documents to tens of millions. Raise the bar on backend engineering practices across the team: not through process for process's sake, but by building systems that make the right thing the easy thing. Longer-term, this role shapes how Heron's entire platform evolves. You'll be the person who ensures our backend can support whatever product throws at it. Who Thrives Here The best person for this role has likely spent 8+ years building and scaling backend systems, with at least a couple of meaningful "at-bats" taking a system from early stage to serious scale. You've probably worked in B2B SaaS and have opinions (earned the hard way) about how to build systems that are both reliable and fast to develop on. More specifically: You have a strong CS foundation and are deeply technical. You write code, review architectures, and debug production issues. You've seen and built backend systems scale at companies growing from Series A to Series C+ (roughly $5M to $100M+ ARR). You know what breaks and when. You have recent production experience with Python and cloud infrastructure. You've dealt with sensitive data at volume: financial, health, or similarly regulated domains. You're an IC at heart. You might set direction and mentor others, but you want to build, not manage. You care about getting things right but also about shipping. We're a startup. Pragmatism matters. What You Can Expect as a Heron Competitive compensation, including equity Based full-time in London or NYC, where most of the team is in-person multiple days per week Your choice of top-of-the-line equipment to fit out your desk in the office Occasional travel for retreats and to work with the team Competitive benefits: health insurance; pension/401k; uncapped annual leave; parental leave Free mental health support via Spill - on-demand access to therapy Weekly company lunches (always inclusive and vegan-friendly - especially if you like Korean or Vietnamese food!) Applicants from any background and gender are welcome and we have a zero tolerance policy on discrimination Visa: Will sponsor.