[Hiring] Senior Fullstack SDK Engineer @Customer.io

Role Description

We’re looking for a curious, AI-forward Fullstack SDK Engineer to join our SDK team and help us build the tools that developers rely on to integrate with Customer.io.

• 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.

Qualifications

• 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.

Requirements

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

Benefits

• Our inclusive benefits package supports your well-being and growth.

Company Description

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.