Senior Fullstack Engineer

Over 7,500 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.

We’re looking for curious, driven fullstack engineers who want to own big things and delight our customers. You’ll design, build, and ship the core product experiences our customers rely on - while helping the team push boundaries on what great communication tools can do

Ownership
You own problems end to end. You move fast, act like an owner, and thrive in ambiguity. You've led complex projects before, whether officially or not, and you're ready to do it again.

Engineers with product taste

You think like a user, not just an engineer. You care about frontend polish, backend performance, and everything in between.

A healthy skepticism for “the way things are done”

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

• Build fullstack features in Go, React, and Ember that power key customer workflows
• Collaborate with others to turn ideas into shipped customer value
• Share knowledge and raise the bar through sharing your progress publicly with short videos, thoughtful writing, and mentorship
• Help evolve our systems to scale with more customers, messages, and use cases
• Leverage AI tools to prototype, move faster, and make better decisions

• 7+ years of experience building and scaling backend services and product-facing features
• Fluency in TypeScript, React (or similar), and a statically typed backend language like Go
• A strong care for frontend polish, backend performance, and the overall customer experience
• Proficiency with APIs, relational databases, and writing testable, performant code
• A bias for action over perfection, and pride in owning technical decisions

We believe in transparency. Starting salary for this role is $150,000 - $200,000 USD (or equivalent in local currency) depending on experience and subject to market rate adjustment.

We know our people are what make us great, and we’re committed to taking great care of them. Our inclusive benefits package supports your well-being and growth, including 100% coverage of medical, dental, vision, mental health, and supplemental insurance premiums for you and your family. We also offer 16 weeks paid parental leave, unlimited PTO, stipends for remote work and wellness, a professional development budget, and more.

See full benefits here →

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.
• Technical Deep Dive (60 mins) - A structured discussion of a project and how you approach real-world engineering problems.
• Take-Home Assignment - Complete a short, realistic task similar to what you’d work on here.
• Assignment Review Calls (2 x 60 mins) - Walk us through your work and discuss tradeoffs, priorities, and how you’d iterate.

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 [email protected].

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.