Senior Software Engineer - Backend Platform

Hi, I'm Manu, Engineering Manager at Customer.io. We're looking for experienced backend engineers who want to build and own the infrastructure that powers one of the most data-intensive platforms in marketing automation — systems that process millions of events per second, orchestrate complex workflows at scale, and keep everything running reliably for thousands of customers worldwide.

You'll work on the Platform team, tackling hard distributed systems problems: designing for fault tolerance, scaling services under real production pressure, and building the foundational layers that every other team at Customer.io depends on. This isn't just maintenance work — you'll shape the architecture of systems that need to be both highly available and constantly evolving.

If you're someone who gets energized by the intersection of scale, reliability, and developer experience — and wants ownership over infrastructure that truly matters — we'd love to talk.

• Deep experience with distributed systems and large-scale backend architecture
• Strong instincts around reliability, observability, and fault tolerance
• Comfort reasoning about performance, capacity, and trade-offs at scale
• Experience with event-driven systems, message queues, or data pipelines is a plus
• A collaborative mindset — you raise the team around you

Over 9,000 companies - from scrappy startups to global brands - use our platform to send billions of emails, push notifications, in-app messages, and SMS every day. Customer.io powers automated communication that people actually want to receive.

We help teams send smarter, more relevant messages using real-time behavioral data. Under the hood: Go, React, Ember and AI help us ship fast and scale with confidence.

You drive technical direction across systems and teams. You move with urgency, build with empathy, and think long-term. You’ve led large-scale infrastructure initiatives and know what it takes to get them over the line.

You think about how infrastructure unlocks customer value. You care about developer experience, system design, and how your work shapes the customer experience.

You bring rigor and creativity. Best practices matter, but never more than forward motion.

• →Design and evolve distributed systems in Go to handle billions of daily events and messages and store and index petabytes of data
• →Lead architectural decisions around performance, reliability, and real-time event processing
• →Improve service-to-service communication through better APIs, messaging systems, and event-driven patterns
• →Work across teams to uncover bottlenecks and system issues, and lead initiatives to resolve them for a smoother customer experience
• →Tackle high-throughput challenges across data pipelines, queues, and scheduling infrastructure
• →Able to debug production systems at scale using effective instrumentation, and resolve issues quickly and confidently
• →Share knowledge and raise the bar through sharing your progress publicly with short videos, thoughtful writing, and mentorship
• →Leverage AI tools to prototype, move faster, and make better decisions

• Significant experience (typically 10+ years) building scalable, distributed systems in Go (or similar statically typed languages)
• Deep experience with databases - relational (MySQL, Postgres) and non-relational (DynamoDB, BigTable) - and how to make them fast
• Comfort working in cloud-native environments (AWS, GCP)
• Familiarity with APIs, observability, and operating production systems
• A bias for action over perfection, and pride in owning technical decisions

No gotchas, no trick questions - just a clear, human process designed to help both of us make an informed decision.

• Application - We review everyone with care. Tell us why you're interested.
• Recruiter Call (30 mins) - Let’s chat about what you’re looking for and how we work.
• Behavioral Interview (60 mins) - Talk with one of our hiring managers. We’ll explore topics like ownership, product thinking, and collaboration.
• System Design Interview (60 mins) - A collaborative system design conversation focused on scaling challenges.
• Coding Interview (60 mins) -Pair with one of our engineers for an agentic live coding interview.

All final candidates will be asked to complete a background check and employment verifications as part of our pre-employment process.

Customer.io recognizes the stifling impact of systemic injustice on diverse communities. We commit to using our influence to increase inclusion and equity within the tech industry. We strive to build an inclusive team culture, implement bias-free hiring practices, and develop community partnerships to expand our global impact.

Zoom is the only video conference platform that we use, virtual interviews will be conducted using the video capability (i.e., not via the chat), and offers will be extended in writing on official Customer.io letterhead. Please be vigilant in all of your job search activity, and if you have any questions please contact jobs@customer.io.

We believe in empathy, transparency, responsibility, and, yes, a little awkwardness. If you’re excited by what you read and want to build software that makes communication better for everyone—apply now.