Customer.io - Senior Fullstack SDK Engineer
Requirements
• Expert-level competency in at least one established programming language, with strong software design and API design fundamentals • Experience building and evolving mature, production-quality software, with a clear understanding of how systems fit together and how other developers consume them • Exceptional fluency with current LLMs and agentic coding tools (e.g., Claude, Cursor, Codex) - using AI to understand unfamiliar codebases, work across languages, and run things in parallel or autonomously • High autonomy in ambiguous environments - you clarify the problem, validate its value, and drive implementation without close direction • Strong written and verbal communication, with the ability to explain technical decisions and tradeoffs clearly • Ability to work effectively across multiple languages and stacks; prior experience in every language we support (Swift, Kotlin, Node, Go) is not required • Nice to have: experience building external-facing SDKs, APIs, or developer tools; experience owning CI, testing, versioning, or release infrastructure; or forward-deployed engineering experience.
Responsibilities
• Build and evolve Customer.io's SDKs across platforms - including Android, iOS, Node, and Go - and the developer tools that support them • Lead SDK initiatives end to end: set technical direction, write the code, manage the release, and own the outcome • Improve SDK delivery infrastructure - CI, automated testing, versioning, publishing, and release processes - so shipping is reliable and low-friction • Partner closely with product and design to turn loosely defined goals into a great developer experience • Use AI agents to make multi-file changes across unfamiliar codebases and languages by scoping the work, writing the prompt, and verifying the output • Bring strong customer empathy to the role - understanding what the engineers integrating with our SDKs actually need, and occasionally engaging directly with them
Benefits
• 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. • Our Process • 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. • Application • Recruiter Call (30 mins) - Let’s chat about what you’re looking for and how we work. • Recruiter Call • Hiring Manager & AI Skills Interview (60 mins) - We'll explore ownership, autonomy, and collaboration, then dig into how you actually use AI in your day-to-day workflow. • Hiring Manager & AI Skills Interview (60 mins) • Practical AI-Enabled Coding Round (60 mins) - A live, collaborative session where you'll extend a sample SDK using AI tools. Wwe want to see how you think and work with AI as part of your process. • Practical AI-Enabled Coding Round (60 mins) • 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.
Apply in one click
Upload My Resume
Drop here or click to browse · Tap to choose · PDF, DOCX, DOC, RTF, TXT