Senior Backend Engineer II

Apollo.io is the leading go-to-market solution for revenue teams, trusted by over 500,000 companies and millions of users globally, from rapidly growing startups to some of the world's largest enterprises. Founded in 2015, the company is one of the fastest growing companies in SaaS, raising approximately $250 million to date and valued at $1.6 billion. Apollo.io provides sales and marketing teams with easy access to verified contact data for over 210 million B2B contacts and 35 million companies worldwide, along with tools to engage and convert these contacts in one unified platform. By helping revenue professionals find the most accurate contact information and automating the outreach process, Apollo.io turns prospects into customers. Apollo raised a series D in 2023 and is backed by top-tier investors, including Sequoia Capital, Bain Capital Ventures, and more, and counts the former President and COO of Hubspot, JD Sherman, among its board members.

Your Role & Mission

As a Senior Backend Engineer at Apollo, you'll be a critical part of a fast-growing company, working on a cross-functional team to build highly scalable systems and set the bar for how we engineer. The way we build has changed: this is an AI-native role. We're not looking for someone who also uses AI, we're looking for someone who thinks with it, forms their own hypotheses, pressure-tests what AI produces, catches its errors, and design more robustly than they could alone.

You'll work in an open, collaborative environment, give and receive hands-on mentorship, and have real opportunities to grow. You'll interface daily with design, front-end, analytics, product, and teams beyond Engineering. You enjoy working cross-functionally to solve hard problems and make an impact. You strive for quality, are obsessed with improving it, automation, monitoring, squashing the bugs that sneak through and you're always investigating performance improvements and better ideas.

Daily Adventures & Responsibilities

• Design and implement highly scalable, highly available backend services with proper monitoring and alerting in place
• Ramp quickly into large, unfamiliar codebases, de-risk your changes, understand blast radius, and ship with confidence
• Use AI as a core part of your workflow: generate and pressure-test approaches, verify and catch AI's mistakes, and stand behind the quality of the code you ship with it
• Drive the full lifecycle of software development: product requirements, architecture, solution design, development, quality assurance, and maintenance, ownership doesn't end at deploy
• Scope and reshape under-specified problems, and write clear design docs that satisfy real product needs
• Partner closely with PMs: translate product intent into technical decisions, surface the technical realities they need to make good calls, and push back on the spec when reality changes the answer
• Mentor others on best practices and effectively share knowledge to up-level the team
• Communicate progress clearly to the product lead, engineering manager, and other stakeholders
• Introduce new technologies and ideas when they earn their place
• Give and receive technical and behavioral feedback; engage in scrum ceremonies, team culture, and collaborate with the team. 

What We're Looking For

• AI-native engineers. You use AI to raise your bar, not just move faster forming your own hypotheses, pressure-testing and verifying AI output, catching its errors, and taking full ownership of code quality regardless of how it was produced. You stay current with a fast-moving toolset.
• Comfort in unfamiliar code. You ramp fast into systems you didn't write, reason about blast radius, and de-risk changes rather than hoping they work.
• Architectural ownership & operational readiness. You design for scale and availability, anticipate failure modes, and build with monitoring and alerting from the start.
• Ownership start to finish. Just because a project has been deployed doesn't mean it's done. You own outcomes , think end to end in terms of product and are customer obsessed
• Collaboration you can trust. You let others speak, seek to understand their viewpoints, and are the kind of teammate people want to build with.
• Product judgment. You care about the customer outcome, make the technical calls that produce a great product, and know when to challenge a spec.
• Growth & learning. You actively improve  your craft, your team, and how you work.
• Proactivity. You act without being told, identify areas of improvement, and drive best practices.
• Comfort with ambiguity. You can operate without a fully-specified problem and bring structure to it.
• Organization & planning. You break large projects into smaller pieces that are easier to estimate and deliver.
• Strong communication. Clear in writing and in person, across technical and non-technical audiences.

Qualifications

• Minimum 5+ years of industry experience in backend development, at least 3-4 years in senior positions, building large-scale applications with right observability.
• Solid computer science fundamentals, data structures, algorithms, and object-oriented design
• Fluency using AI tools in real development work, plus the judgment to verify and pressure-test their output rather than trusting it blindly
• Experience developing distributed web applications
• Write code that is comprehensible, well-structured, and highly performant
• Experience with database modeling (SQL or NoSQL both fine)
• Experience using and designing RESTful services

Must have: Curiosity, AI-native engineering judgment, communication skills, problem solving.

Nice to have: BS or MS in Computer Science, Computer Engineering, or similar; GCP, Kubernetes, Docker, Mongo, Redis, Ruby on Rails, Microservices, Machine Learning

Apollo.io Tech Blog: deep dives into engineering, product design, and company-culture stories from the Apollo team — behind-the-scenes insight into how Apollo builds and scales its B2B sales platform.

We are AI Native

Apollo.io is an AI-native company built on a culture of continuous improvement. We’re on the front lines of driving productivity for our customers—and we expect the same mindset from our team. If you're energized by finding smarter, faster ways to get things done using AI and automation, you'll thrive here.

Why You’ll Love Working at Apollo

At Apollo, we’re driven by a shared mission: to help our customers unlock their full revenue potential. That’s why we take extreme ownership of our work, move with focus and urgency, and learn voraciously to stay ahead.

We invest deeply in your growth, ensuring you have the resources, support, and autonomy to own your role and make a real impact. Collaboration is at our core—we’re all for one, meaning you’ll have a team across departments ready to help you succeed. We encourage bold ideas and courageous action, giving you the freedom to experiment, take smart risks, and drive big wins.

If you’re looking for a place where your work matters, where you can push boundaries, and where your career can thrive—Apollo is the place for you. 

Learn more here!