Software Engineer, Pub/Sub

About this role

The Pub/Sub team owns the core backend that underpins Ably's entire edge messaging platform. This is a rare opportunity to work on genuinely hard distributed systems problems at planet scale; designing and improving the infrastructure that developers and their users depend on in production every day.

You'll be hands-on, driving the development of new functionality and initiatives to scale and improve Ably's core Pub/Sub platform. We work in an AI-first engineering culture: AI tools are part of how we plan, prototype, and iterate - but engineers own every technical decision, and human judgment is the quality bar that everything is measured against.

Day to day you will

• Deliver key platform functionality.  You'll work across Ably's realtime products including our low-level Pub/Sub APIs, our LiveObjects state synchronisation layer, and AI Transport, the messaging backbone purpose-built for AI agent communication, focussing on shipping new features, performance improvements, bug fixes and maintenance.
• Work fluently with AI tooling. You'll use AI tools for planning, spike work, code generation, and documentation, while taking full ownership of correctness, architectural quality, and what actually ships. Fast iteration is expected; shortcuts in quality are not.
• Solve hard distributed systems problems. You'll collaborate with a talented engineering team to work through genuinely interesting and challenging technical problems.
• Stay driven by 'Developer First' principles. You'll work closely with other engineers to identify and address the most important problems developers face when building on Ably.
• Push to see your work in customers' hands. You'll move with urgency to ship, because you care about the impact your work has on the developers and companies building on our platform.

We'd love to talk if you have

• A strong interest in, or direct experience with, distributed systems and large-scale infrastructure.
• Experience working with or building messaging queues, pub/sub systems, or streaming systems at scale.
• Extensive experience with a high-level server-side language (Node.js or Go preferred).
• The ability to self-start, work through ambiguity, and make good decisions without a lot of hand-holding.
• A practical relationship with AI tooling. You use it to go faster and think more clearly, and you know where to apply rigour that AI alone can't provide.
• A transparent, collaborative 'build in the open' mindset. You're comfortable sharing your work publicly, whether that's writing about what you're building, talking about technical decisions, or contributing to the broader developer conv