Software Engineer, Pub/Sub

Our everyday digital experiences are in the middle of a realtime revolution: chatting alongside a livestream, getting realtime financial updates, or working with colleagues in a shared online space. Consumers now expect realtime as standard, and Ably powers a large part of it.

We put developers first. Our products help teams build, extend, and deliver realtime digital experiences, delivering over 700 billion messages to more than 2 billion devices every month. Teams at HubSpot, Fin, Dialpad, NASCAR, Sportsbet, and General Motors all build on Ably.

Working at Ably means helping build the infrastructure that will shape the next generation of the internet. More of what people do online is becoming live, shared and interactive, which only makes what we build more relevant and more necessary. AI is the latest place that shows up. There's still so much to build, and we'd like your help with it.

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.

You can read more about the core concepts of working on a truly distributed system in our blog post here.

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 conversation around the problems Ably solves.
• Experience in dynamic, early-stage environments where adaptability and resourcefulness are core skills.

Bonus points if you have

• Experience building developer-first products.
• Experience with products brought to market through a product-led growth approach.

What’s it like to work at Ably?

You'll join a team of around 60 people, working directly alongside senior engineering and leadership. No layers, no bureaucracy, and real ownership from day one.

Remote-first

We hire the best people wherever they are across the UK and Europe, trust them to own their work, and share decisions and feedback openly. Twice a year, in February and August, we all meet in person, and we expect everyone to be there.

Remote-first comes with trade-offs. On one side: flexibility, no commute, long stretches of focus time, and a wider pool of people to hire from. On the other: it can feel isolating, relationships take effort to build, and you miss the chance conversations an office creates. As our only recruiter, you'll need to manage your own time and stay close to the hiring managers and candidates you work with.

If you do your best work with trust and autonomy, this will suit you. If you'd rather have an office around you every day, it probably isn't the right fit.

Our six values shape how we work day to day:

• Open for all. We default to sharing openly: source, decisions, and feedback, with open minds to match.
• Tech needs humanity. We build with empathy, for colleagues and developers alike.
• Even the best do better. We keep raising our own bar, driven by curiosity, not complacency.
• Bias for action. Once we know enough to act, we act, rather than waiting for certainty.
• Dependable by default. We take real ownership of what we ship and what we promise.
• Bold creativity wins. We treat big constraints as a reason to think differently, not less.

You can read more about how we defined these values on our blog, and see the team behind them on our careers page.

Diversity, inclusion, and belonging at Ably

We believe our differences as individuals are what make us great. Our people are at the heart of what we do, and we encourage everyone to be their most authentic self at Ably: we see inclusivity and openness as fundamental to our long-term success. We encourage applications from all backgrounds regardless of age, disability, gender, sexual orientation, parental status, race, religion, educational background, or neurodiversity. Ably has an amazing opportunity ahead of us, and we want anyone to be able to contribute to it.

If you enjoy working as part of a technology company, value open source, and love solving hard problems, we'd love to hear from you, regardless of whether you fit the job description exactly or not. If in doubt, drop us an email;; we're happy to give you advice on your application.

What you'll get

• A remote-first and flexible work environment. Our London office (next to Old Street) is there whenever you want it. Aside from our company get-togethers, you're welcome to work wherever suits you best.
• Equity. We're a growing start-up, and we want everyone to share in the company's success through our EMI share options programme.
• Enhanced holiday allowance: 28 days of paid annual leave (27 regular days, plus a day off to enjoy your birthday).
• Enhanced parental leave, so you can spend time with your new family member: up to 16 weeks fully paid for primary caregivers and 4 weeks for secondary, depending on length of service.
• A home workstation budget of £500 on joining (and £150 per year after that), so your home office serves you well.
• A personal learning and development budget of £1000 a year, plus 5% L&D time during working hours to build your skills.
• Private healthcare with BUPA.
• A medical cash plan covering a range of medical and dental costs.
• Mental wellbeing coaching and counselling from Self Space.
• A monthly wellbeing budget via Juno.
• Life assurance and income protection.
• Access to Tech and Cycle to Work schemes.
• A weekly snack allowance for our end-of-week "Need to Know" meeting.
• A fully-paid one-month sabbatical after five years with Ably.

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