---
title: 'Senior Fullstack SDK Engineer at Customer.io'
canonical: 'https://feeny.ai/job/senior-fullstack-sdk-engineer-customer-io-americas-fkcavs4jky9w'
type: 'job'
last_seen: '2026-09-12'
---

# Senior Fullstack SDK Engineer at Customer.io

- **Company:** Customer.io
- **Location:** Americas
- **Work type:** remote
- **Posted:** 2026-07-21
- **Last confirmed live:** 2026-09-12
- **Apply:** https://job-boards.greenhouse.io/customerio/jobs/8076081

## Job description

Hi, I’m Josh, Engineering Manager at [Customer.io](http://customer.io/). 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](http://customer.io/).

About [Customer.io](http://customer.io/)

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](http://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.

## What We Value

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 developer using your tools, not just an engineer building them. You care about API design, developer experience, 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.

## What You’ll Do

- Build and evolve [Customer.io](http://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

## What we're looking for

- 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.

## Compensation & 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.

[See full benefits here →](https://customer.io/careers#:~:text=our%20collective%20success.-,BENEFITS,-Our%C2%A0)

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.
- Recruiter Call (30 mins) - Let’s chat about what you’re looking for and how we work.
- 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.
- 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.

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

[Customer.io](http://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](http://customer.io/) letterhead. Please be vigilant in all of your job search activity, and if you have any questions please contact jobs@customer.io.

Join us!

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.

## About Customer.io

## Company Overview
- **One-liner**: Customer.io is an AI-powered customer engagement platform that helps businesses send personalized, data-driven messages across email, SMS, push notifications, in-app messages, and webhooks.
- **Entity Type**: Private (backed by venture capital)
- **Headquarters**: Portland, Oregon, USA (with a fully remote, globally distributed team)
- **Founded**: 2012
- **Founders**: Colin Nederkoorn (CEO)

## Core Business
- **Primary Industry**: Marketing technology / Customer engagement & messaging infrastructure
- **Target Customers**: B2B — mid-market to enterprise companies (e.g., Notion, LESMILLS+, Angi) seeking to automate and personalize customer communications at scale
- **Mission/Purpose**: To create a world where you have one unified view of your audience and a single place where unlimited, real-time data powers more effective engagement.

## Products & Services
- **Customer.io Journeys**: A visual workflow builder for creating automated, multi-channel customer journeys (email, SMS, push, in-app) triggered by real-time user behavior.
- **Customer.io Data Pipelines**: Real-time event streaming and audience segmentation tools to unify first-party data from multiple sources.
- **Customer.io Messaging API**: Programmatic infrastructure for sending triggered messages across channels.
- **AI-Powered Features**: Leverages artificial intelligence to optimize message timing, content personalization, and channel selection.

## Market Standing
- **Valuation/Total Funding**: Not publicly disclosed (company is private).
- **Key Metric**: Over 9,000+ brands use the platform; processes millions of daily API calls and serves a large base of active users.
- **Notable Investors/Partners**: Not publicly disclosed in available sources. High-profile customers include Notion, LESMILLS+, and Angi.
- **Growth Signals**: The company is actively hiring across Engineering, Sales, Marketing, Data Science, and Customer Experience (19 open roles as of the latest careers page), indicating continued expansion. They have a global, remote-first team of 263 employees.

## Competitive Advantages
- **Real-time data infrastructure**: Unlike many marketing tools that batch data, Customer.io processes real-time behavioral events, enabling truly instant, context-aware messaging.
- **Unified multi-channel orchestration**: A single platform to manage email, SMS, push, in-app, and webhooks — reducing tool sprawl.
- **Developer-friendly approach**: Strong API and data pipeline tools appeal to product and engineering teams who want to build custom engagement logic.
- **Privacy-first with first-party data**: Designed to leverage brands’ own customer data, aligning with post-cookie and privacy-regulation trends.

## Strategic Focus
- **AI integration**: Embedding AI into personalization and orchestration to improve message relevance and campaign outcomes.
- **Scaling globally**: Hiring across EMEA and Americas to support a growing international customer base.
- **Deepening product capabilities**: Expanding data pipelines and automation features to serve larger, more complex enterprise use cases.

## Why Work Here
- **Fully remote and async-first**: A 100% remote, globally distributed company with asynchronous operating model, collaboration hours across time zones, and minimal unnecessary meetings.
- **Generous compensation & benefits**:
  - Competitive salary and equity
  - 100% paid medical, dental, vision, and mental health insurance for employee and family
  - Up to 5% 401k matching (dollar-for-dollar)
  - Unlimited PTO with a recommendation of at least 20 vacation days
  - 16 weeks paid parental leave (birth, adoption, foster)
  - 6 weeks paid family medical leave
  - $2,000/year professional development budget
  - $1,500 home office setup stipend
  - $250/month remote work stipend (internet, phone)
  - Up to $300/month co-working space reimbursement
  - $1,500/year healthy living stipend
  - Financial wellness provider access
  - Paid sabbatical after 5 years
- **Culture**: Strong emphasis on DEIB with Ami Resource Groups (ARGs), recognition programs, casual learning gatherings, and volunteer opportunities. Values include genuine connections, open communication, accountability, and celebrating individuality.
- **Engineering culture**: Opportunity to work with talented peers on impactful, scalable infrastructure that processes billions of events. Emphasis on autonomy and responsibility.

## Sources
1. [Customer.io Careers Page](https://customer.io/careers)
2. [Customer.io About Page](https://customer.io/about)
3. [Customer.io Official Website](https://customer.io/)
4. [Customer.io Greenhouse Job Board](http://job-boards.greenhouse.io/customerio)
5. [Built In Company Profile](https://builtin.com/company/customerio)

## Other roles at Customer.io

- [Contract Accounts Payable Manager](https://feeny.ai/job/contract-accounts-payable-manager-customer-io-americas-8wayezqqg4tw) — Americas
- [Sr Sales Manager, Mid-Market - USA (Remote)](https://feeny.ai/job/sr-sales-manager-mid-market-usa-remote-customer-io-americas-v37dkjzrqtwz) — Americas
- [Global Controller](https://feeny.ai/job/global-controller-customer-io-americas-57bwecz6xp8r) — Americas
- [Senior Recruiter - GTM - USA (Remote)](https://feeny.ai/job/senior-recruiter-gtm-usa-remote-customer-io-americas-3zwzhq34zydn) — Americas
- [Senior Technical Recruiter](https://feeny.ai/job/senior-technical-recruiter-customer-io-americas-stnqbdpr4srt) — Americas
- [Senior Manager, Information Technology](https://feeny.ai/job/senior-manager-information-technology-customer-io-americas-7aa59qd0mmjh) — Americas
- [Mid-Market Account Executive, EMEA](https://feeny.ai/job/mid-market-account-executive-emea-customer-io-emea-19k0rmg89g78) — EMEA
- [Product Manager](https://feeny.ai/job/product-manager-customer-io-americas-q7q5sv3gmcdx) — Americas
- [Engineering Manager](https://feeny.ai/job/engineering-manager-customer-io-americas-ft7psdsc8gpk) — Americas
- [Director, GTM Finance](https://feeny.ai/job/director-gtm-finance-customer-io-americas-dhejb2txwfkm) — Americas