Senior Engineer

About Siren
Siren is building revenue agents for consumer brands. Today, brands spend billions trying to reach customers through emails, ads and SMS campaigns that most people ignore. We’re building something different: AI agents that build real, one-to-one relationships with every customer.

Our agents live in the messaging apps customers already use, like iMessage and WhatsApp. They help with what a customer just bought, learn what they want next in their own words, and proactively bring them back to buy it. They don’t just answer questions. They take action, make decisions and drive revenue on their own, so the brand doesn’t have to build any campaigns.

And customers actually talk back. More than 55% have real two-way conversations with our agents, and those customers drive 4X more repeat revenue.

Where we are today:
● Live with consumer brands, including some of the largest brands on Shopify
● Contracts with some of the largest retailers, and growing fast
● Backed by top VCs and angels

We’re two HBS and Wharton founders and a CTO with 20+ years of combined experience at Amazon, American Express, Stripe and Google Shopping.

Why join now
Consumer agents like Instinct and Muse are booming, and consumers are adopting these technologies faster than brands are. As more shopping runs through agents, brands need agents on their side of the table, representing their needs in every transaction. We’re building the first ones.
We’ve proven that customers will engage with AI agents in a way they never did with traditional marketing, and brands are coming to us faster than we can bring them live.
We’re hiring our second engineer at a pivotal moment. You’ll join a team of two founders and our CTO to scale the business as quickly as possible, building the technology to bring these agents to thousands of brands and millions of customers.

● You’ll shape the company from the ground up. You’ll join a tiny engineering team and help define the product, the architecture and the engineering culture.
● What you build ships. You won’t spend months on features that never launch. Your work goes into production, talks to real customers and drives measurable revenue for real businesses.
● You’ll have real ownership from day one. You won’t wait for tickets or work through layers of process.
● It’s early, but it’s working. Your work will matter a lot, and there’s already a live product, real brands and more demand than we can serve.
● The technical problems are hard. We’re building reliable, long-running AI agents that:
○ Remember customers
○ Reason across complex business systems
○ Take real-world actions
○ Represent the brand in every transaction, including with consumers’ own agents
○ Run autonomously at scale

The role
You’ll work closely with our CTO and both founders across the whole product:
● Backend
● Data
● Infrastructure
● Integrations
● The agent itself

Take a problem, build it, verify it, ship it.
This is a hands-on build role with real ownership of what you ship. Feedback loops are short and there’s very little process. Real customers are on the other end from your first week.

What you’ll work on
● The AI agent. Design agent workflows that:
○ Reason
○ Use tools
○ Keep context across conversations
○ Take actions on behalf of brands
● Making the agent reliable in production. Build the systems that keep its output reliable, including:
○ Memory
○ Evaluation
○ Orchestration
○ Latency
○ Safety
● Core product features across the stack. Everything from database schema and APIs to internal tools and brand dashboards.
● Integrations that connect our agents to:
○ Shopify and other ecommerce platforms
○ Messaging platforms
○ Logistics platforms
○ Customer data and the other tools brands run on
● Infrastructure:
○ Deploys
○ Migrations
○ Cloud infrastructure
● Reporting and analytics for the brands we serve
● How we build. Make foundational technical decisions, set best practices and help define how we work as the team grows.

Who we’re looking for
We’re looking for an exceptional engineer who wants to build, move fast and take ownership.
● You can build and ship production systems on your own
● You’re comfortable working across the stack and learning whatever a problem needs
● You’re excited about LLMs and AI agents, and about making them reliable enough for real customers
● You have strong product instincts. You care about what you’re building and why, not just how.
● You do well in an early-stage environment where priorities move quickly and you have room to figure things out
● You hold yourself to high standards and take full ownership of your work
● You have a bias toward shipping

You don’t need years of experience building AI agents. We care more about engineers who are exceptionally good at solving hard problems and excited to learn.

Required skills
● Experience building production systems you also operated
● Strong TypeScript and Node.js
● Solid SQL and relational data modeling, ideally PostgreSQL. You can:
○ Design a schema
○ Write a migration
○ Reason about what a query costs
● Experience integrating third-party APIs:
○ REST and GraphQL
○ Webhooks
○ OAuth
● Cloud infrastructure: you’ve deployed and operated services on AWS, GCP or similar, and you’re comfortable with:
○ Containers
○ Secrets
○ CI/CD
● Front-end capability: enough React and Next.js to build and maintain internal tools well
● Clear written communication
Nice to have
● Shopify app development, or ecommerce integrations generally
● LLM and agent systems
● Infrastructure as code
● Messaging or SMS products
● Telephony
● Experience on a founding or very early team
How we work
● We verify rather than assume. We care less about how fast you write code than whether you can show it does what you think it does. Engineers who confirm behavior rather than infer it do well here.
● We write things down. We record decisions and the reasoning behind non-obvious choices.
● Small team, wide scope. You’ll touch most parts of the product and own what you ship.
● Low process. No endless meetings and no process for the sake of process.

Why Siren
Most AI products today are tools that help people do their jobs faster. We’re building software that does the work itself.
We believe every consumer brand will have its own AI agents, the way every brand has a website today. We’re building the platform that makes that possible. As our second engineer, you’ll work alongside the founders and help build the technical foundation of the company at the very start of its growth.

A note on pace
This role is demanding. We’re growing fast, there’s a lot to build, and both the pace and the bar are high. It’s not a fit if you want a narrow scope or a low-intensity environment.