Senior Fullstack SDK Engineer - Customer.io

About the Role

Customer.io is looking for a curious, AI-forward Senior Fullstack SDK Engineer to join our SDK team. You will build and maintain the tools that developers rely on to integrate with our platform, which powers automated communication for over 9,000 companies.

What You’ll Do

• Build & Evolve: Develop and maintain SDKs across platforms (Android, iOS, Node, Go) and supporting developer tools.
• Lead Initiatives: Set technical direction, manage releases, and own outcomes end-to-end.
• Improve Infrastructure: Enhance CI, automated testing, versioning, and publishing processes for reliable, low-friction delivery.
• Collaborate: Partner with product and design to define and deliver a superior developer experience.
• Leverage AI: Utilize AI agents to manage multi-file changes across unfamiliar codebases, scope work, and verify outputs.
• Customer Empathy: Engage directly with developers to understand their needs and pain points.

What We’re Looking For

• Technical Expertise: Expert-level competency in at least one established programming language with strong software and API design fundamentals.
• Production Experience: Proven track record of building and evolving mature, production-quality software.
• AI Fluency: Exceptional skill using LLMs and agentic coding tools (e.g., Claude, Cursor, Codex) to navigate codebases and automate tasks.
• Autonomy: Ability to thrive in ambiguous environments, clarify problems, and drive implementation independently.
• Communication: Strong written and verbal skills to explain technical decisions and tradeoffs.
• Versatility: Ability to work across multiple languages and stacks (Swift, Kotlin, Node, Go).

Benefits

• 100% coverage of medical, dental, vision, mental health, and supplemental insurance for you and your family.
• 16 weeks paid parental leave.
• Unlimited PTO.
• Stipends for remote work and wellness.
• Professional development budget.

Our Process

1. Application Review: We review every application with care.
2. Recruiter Call (30 mins): Discuss your goals and our working style.
3. Hiring Manager & AI Skills Interview (60 mins): Explore your approach to ownership, autonomy, and AI-assisted workflows.
4. Practical AI-Enabled Coding Round (60 mins): A collaborative session extending a sample SDK using AI tools.