Head of Engineering in London

Meet Siena. Siena is the first intelligence layer for customer experience. We are creating an operating system of AI agents that learn, remember, and act across every customer touchpoint—from support conversations to shopping experiences to voice and social media interactions. Siena doesn’t just automate support; it powers shopping agents, builds persistent customer memory, generates actionable business insights, and creates empathetic interactions that feel human. We are transforming how businesses understand and connect with their customers, turning every interaction into intelligence that makes the next one better.

The team is a small, distributed group that punches way above our weight. Every person here has outsized impact because we’ve built leverage into everything we do. This philosophy makes us faster and, frankly, more fun to work with. If you’re excited about building something that doesn’t exist yet, keep reading. We’re building agents that don’t just respond to customers—they remember them, learn from every interaction, and connect experiences across channels.

As Head of Engineering at Siena, you will set the technical vision for the first intelligence layer in customer experience—AI pipelines, evaluations, integrations, multi-agent orchestration. Your job: decide where we build, what we buy, and how we scale. You will shape Siena’s technical strategy, influence product direction, and build the culture. You will operate as a peer to product, design, and revenue leadership. And you still prototype with Cursor and Claude Code on weekends because that’s who you are.

What you’ll do:

• Set technical roadmap aligned to business goals—make build vs buy decisions at company level.
• Double our engineering team over 12-18 months—design team structures, develop leaders, coach and be an example for what’s possible with agentic coding.
• Stay hands-on with AI tools—write prototypes, review critical PRs, ship experiments, maintain technical credibility.
• Operate cross-functionally—partner with product/design/revenue as a peer, shape company strategy.
• Drive velocity at scale—ship weekly, cut scope based on learning, rally teams through ambiguity.
• Build culture that attracts top talent—create momentum through energy, establish practices that scale.

What we’re looking for:

• You’ve scaled teams to 30+ successfully.
• You still code using AI tools like Cursor, Claude Code, Codex, Lovable, v0.
• You have technical depth with AI-native fluency.
• You’re comfortable with customers—join enterprise calls, understand their technical pain, earn trust at exec level.
• You have high agency—take bets, shape direction proactively.
• You’ve led teams that shipped regularly at scale.
• You’ve made technical decisions that shaped company direction.
• You’ve developed multiple leaders from ICs.
• You’ve maintained velocity during high growth.
• You’ve built with relevant technology: conversational AI, event-driven systems, LLM applications, CX platforms, e-commerce, API integrations.
• You zoom from strategy to debugging fluidly.
• You bring infectious energy, positive culture builder mindset.
• You have startup DNA—comfortable with ambiguity, move fast.

Why Siena:

• Meaningful impact. Your work directly shapes our product and company.
• Globally distributed team working at the bleeding edge of CX and AI.
• Great salary plus the opportunity for equity or stock grants.
• Learning budget. If you’re growing, so are we.
• The thrill of building something new. Join us at a stage where your contributions matter most.
• AI-fluency. Make AI your second nature.
• Tackle unsolved problems. We’re redefining how customer experience will look like in the next decades.

Our values:

The people who thrive here are curious, customer-obsessed, and take ownership without being asked. They fix problems first and explain later. They’re direct about feedback—both giving and receiving it—because they care more about getting things right than being polite. They maintain high standards while moving at startup speed, and they build real relationships with teammates because they know that’s how great work gets done. When things get tough, they adapt and keep pushing forward.

Our approach to AI:

The people who thrive here treat AI like a natural extension of themselves. They’ve built their own ecosystem of agents – some for research, others for debugging, writing, analysis, or code. They know which AI works best for what problem. Everyone gets premium accounts (ChatGPT, Claude, Perplexity Pro, Cursor, Lovable) plus a quarterly budget for new tools. But the magic happens in how we share knowledge. Demo days where someone shows off a clever workflow. Slack threads about which model handles a specific use case better. Learning from each other’s AI workflows. At Siena, we’re not just looking for people who can do a job. We’re looking for people who want to break boundaries, create the future, and reshape industries. If that’s you, we look forward to your application.

Siena provides equal employment opportunities to all employees and applicants for employment without regard to race, colour, religion, sex, national origin, age, disability, genetics, sexual orientation, gender identity, or gender expression. We are committed to a diverse and inclusive workforce and welcome people from all backgrounds, experiences, perspectives, and abilities.