Principal Software Engineer (Hybrid, San Francisco)
apolloio · Hybrid, San Francisco
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
50 million to date and valued at
## 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!
Careeroza — One-stop Zone for Aspirants
Study material, Careeroza mentorship, tech jobs, and career guidance on careeroza.com.
Public study materials
- Express.js — Web APIs & middleware (expressjs)
- Application setup · basic
- Routing deep dive · basic
- 1. MVC / Layered Architecture · medium
- Validation · medium
- File uploads · medium
- Sessions & auth (stateful) · medium
- Passport & strategies · medium
- Templating & SSR · medium
- WebSockets & SSE · medium
- Security middleware · advance
- Reverse proxies & trust · advance
- Performance · advance
- API design & versioning · advance
- Testing with Supertest · advance
- GraphQL & tRPC (overview) · advance
- Deployment checklist · advance
- Middlewares · basic
- Request & Response · basic
- AWS Crash Course (AWS)
- What is Cloud ? · basic
- What is AWS ? · basic
- If not cloud ? · basic
- Cloud Computing · basic
- AWS Pricing · basic
- AWS Shared Responsibility Model · basic
- AWS Management Console · basic
- AWS SDKs · basic
- AWS IAM · medium
- Users, Groups, Roles · medium
- Policies · medium
- AWS Organizations · medium
- AWS Cognito · medium
- AWS Directory Service · medium
- AWS KMS (Key Management Service) · medium
- AWS Secrets Manager · medium
- AWS Shield · medium
- AWS WAF · medium
- AWS Inspector · medium
- AWS GuardDuty · medium
- EC2 · advance
- Launching EC2 Instances · advance
- EBS Volumes · advance
- Security Groups · advance
- Key Pairs · advance
- Elastic IP · advance
- User Data Scripts · advance
- Auto Scaling · advance
- Load Balancers · advance
- ALB · advance
- NLB · advance
- Serverless Compute ,AWS Lambda, Lambda Layers · advance
- Event-Driven Architecture · advance
- ECS · advance
- EKS · advance
- Django (Django)
- What is Django · basic
- Installing Django · basic
- Features of Django · basic
- MVT Architecture · basic
- Django vs Flask · basic
- Creating Project & Creating App · basic
- Django Project Structure · basic
- URL Routing · basic
- Views · basic
- Templates · basic
- Static & Media Files · medium
- Models · medium
- ORM (Object Relational Mapping) · medium
- Model Relationships · medium
- Migrations · medium
- Django Admin · medium
- Forms · medium
- Authentication · medium
- Authorization · medium
- Middleware · medium
- Signals · medium
- Class Based Views Deep Dive · advance
- Generic Views · advance
- File Handling · advance
- Django REST Framework (DRF) · advance
- Advanced ORM · advance
- Caching · advance
- Asynchronous Django · advance
- Background Tasks · advance
- Interview Questions · interview-questions
- System Designing (System Designing)
- Day-1 : What is system Designing ? · basic
- Day-2 : Vertical vs. Horizontal Scaling · basic
- Day-3:How to do vertical scaling ? · basic
- Day4:How to do horizaontal scaling ? · basic
- Day:5TCP vs UDP · basic
- Day6:IP & DNS · basic
- Day7:Client-Server Model · basic
- Day8:HTTP & HTTPS · basic
- Databases (SQL vs NoSQL) · medium
- Caching · medium
- Day9:Latency & Throughput · basic
- Load Balancing · medium
- Indexes & Query Optimization · medium
- CDN · medium
- Proxies · medium
- Message Queues · medium
- Horizontal vs Vertical Scaling · medium
- Database Replication · advance
- Database Sharding · advance
- Consistent Hashing · advance
- CAP Theorem · advance
- Rate Limiting · advance
- Service Discovery · advance
- Event-Driven Architecture · advance
- API Gateway · advance
- Distributed Consensus · expert
- Microservices · expert
- Observability · expert
- Idempotency · expert
- PACELC Theorem · expert
- Two-Phase Commit · expert
- Back-of-Envelope Estimation · expert
- Designing for Failure · expert
- Node.js — Server-side JavaScript (nodejs)
- Getting started · basic
- JavaScript on the server · basic
- CommonJS modules · basic
- ES modules (ESM) · basic
- npm & package management · basic
- Asynchronous JavaScript in Node · basic
- The event loop · basic
- Essential core utilities · basic
- process & configuration · basic
- File system basics · basic
- HTTP & HTTPS servers · medium
- Streams · medium
- Events & EventEmitter · medium
- Advanced filesystem · medium
- crypto · medium
- Compression & encoding · medium
- Child processes · medium
- net, dgram & DNS · medium
- readline, timers & scheduling · medium
- Testing & diagnostics (intro) · medium
- Worker threads · advance
- cluster & multi-process scaling · advance
- Performance & tuning · advance
- Debugging & observability · advance
- Security hardening · advance
- Native addons & N-API · advance
- Architecture patterns · advance
- Graceful shutdown · advance
- 100 Questions · interview questions
- Python (Python)
- Python Fundamentals · basic
- Control Flow · basic
- Strings · basic
- Collections / Data Structures · basic
- Functions · basic
- Modules and Packages · basic
- File Handling · basic
- Exception Handling · basic
- Object-Oriented Programming (OOP · medium
- Advanced Python Concepts · advance
- Functional Programming · advance
- Multithreading & Multiprocessing · advance
- Async Programming · advance
- JavaScript (JavaScript)
- JS Introduction · basic
- Variables & Data Types · basic
- Operators · basic
- Control Flow · basic
- Functions · basic
- Scope & Execution · basic
- Closures · basic
- Objects · basic
- Arrays · basic
- Strings · basic
- DOM Manipulation · basic
- Browser APIs · medium
- Asynchronous JavaScript · medium
- Fetch & APIs · medium
- ES6+ Features · medium
- OOP in JavaScript · medium
- Prototype & Inheritance · advance
- Advanced Functions · advance
- Memory Management · advance
- Error Handling · advance
- Modules · advance
- Advanced Async Concepts · advance
- Functional Programming · advance
- JavaScript Internals · advance
- Performance Optimization · advance
- MongoDB — Documents & data modeling (MongoDB)
- Introduction · basic
- Shell, Compass & tools · basic
- Databases & collections · basic
- CRUD operations · basic
- Indexes deep dive · medium
- Explain plans & performance · medium
- Aggregation framework · medium
- Schema design patterns · medium
- Mongoose basics · medium
- Mongoose advanced · medium
- Drivers & connection · medium
- Operators for updates & arrays · medium
- Replication & read preferences · advance
- Write concern & read concern · advance
- Multi-document transactions · advance
- Change streams · advance
- Sharding (overview) · advance
- Atlas Search & full-text · advance
- GridFS & large files · advance
- Backup, restore & ops · advance
- SQL (SQL)
- SQL Fundamentals · basic
- Database Operations · basic
- Table Operations · basic
- CRUD Operations · basic
- Filtering & Operators · basic
- SQL Functions · basic
- GROUPING Data · basic
- Joins · medium
- Constraints · basic
- Subqueries · medium
- Set Operators · medium
- Views · medium
- Indexes · medium
- Normalization · advance
- Transactions · advance
- Stored Procedures & Functions · advance
- Triggers · advance
- Advanced SQL · advance
- Query Optimization · advance
- Database Design · advance
- SQL Security · advance
- Backup & Recovery · advance
- Questions · interview questions
- System Architecture (System Architecture)
- Fundamentals of System Architecture · basic
- Distributed System Basics · basic
- System Reliability Concepts · basic
- Scaling Concepts · basic
- Networking Basics · basic
- Web Communication · basic
- API Communication · basic
- Proxy & Delivery Systems · basic
- Web Architecture Basics · basic
- Rendering Architectures · basic
- Frontend Advanced Concepts · basic
- Message Queue Basics · medium
- What is Load Balancer · medium
- Load Balancing Algorithms · medium
- API Design Basics · medium
- API Protection · medium
- Authentication Basics · medium
- Security Tokens · medium
- Security Threats · medium
- Encryption & Security · medium
- SQL Database Basics · medium
- SQL Scaling Concepts · medium
- NoSQL Databases · medium
- Database Optimization · medium
- Replication Strategies · medium
- Caching Basics · medium
- Cache Storage Systems · medium
- Cache Strategies · medium
- Event-Driven Systems · advance
- Queue Reliability · advance
- Microservices Basics · advance
- Microservice Communication · advance
- Distributed Transactions · advance
- DevOps Basics · advance
- Automation Tools · advance
- Deployment Strategies · advance
- Monitoring Basics · advance
- Monitoring Tools · advance
- Distributed System Concepts · advance
- Distributed Algorithms · advance
- Angular (Angular)
- Angular Fundamentals · basic
- Project Structure · basic
- Components & Templates · basic
- Data Binding · basic
- Directives · basic
- Pipes · basic
- Component Communication · basic
- Lifecycle Hooks · basic
- Routing Basics · basic
- Routing · basic
- API Calls · basic
- Forms · medium
- Routing · medium
- Services & Dependency Injection · medium
- RxJS & Observables · medium
- Authentication & Security · medium
- Component Interaction · medium
- State Management Basics · medium
- Error Handiling · medium
- Perfomance Basic · medium
- Real World Features · medium
- Advanced Angular Architecture · advance
- Change Detection · advance
- Advanced RxJS · advance
- State Management · advance
- Dynamic Rendering · advance
- Perfomance Optimization · advance
- Modern Angular · advance
- STAR (Situation, Task, Action, and Result) (Situation Based Questions)
.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.
About Apollo
Apollo is the AI-powered go-to-market platform that helps revenue teams find, engage, and convert their best customers. We combine a database of more than 210 million contacts and 35 million companies with an agentic end-to-end GTM platform, and more than 500,000 companies rely on us to run their go-to-market motion. We are profitable, growing fast, and rebuilding the product around AI and agents.
Your role and mission
You will set technical direction at the level of the whole engineering organization. You will own the hardest, most ambiguous, and highest-stakes technical bets, the ones that shape the product for years, and you will be a force multiplier across many teams. Your judgment will be a reference point for how we build, and your impact will be felt org-wide rather than on any single team.
What you will do
• Own the technical direction of Apollo's most critical and most ambiguous problems, across team and organizational boundaries
• Make the architectural bets that shape the product and platform over multiple years, and be accountable for how they play out
• Set the technical strategy for the rebuild around AI and agents, and turn it into direction teams can execute
• Raise the engineering bar across the whole organization through the standards, patterns, and decisions you drive
• Multiply the output of engineers and teams far beyond your own code, through design, review, and mentorship of our most senior engineers
• Partner with engineering and product leadership as a peer on where the technology needs to go.
How we work: AI-native by default
You set the standard for what AI-native engineering looks like at the highest level. You use agents to move faster on the hardest design, investigation, and implementation work, you define the practices other engineers adopt, and you find the step-change bets where AI reshapes how we build the product, not just how fast we ship.
What we are looking for
• A track record of setting technical direction that shaped a product or platform across an entire engineering organization
• Depth across distributed systems and architecture, and command of the reliability, scale, and cost tradeoffs behind company-defining decisions
• The judgment to make the hardest calls under ambiguity, and the influence to align many teams behind them
• A record of multiplying the most senior engineers around you. Genuine, current fluency with AI-assisted development, and a clear point of view on where AI takes engineering next
Our tech stack
React on the front end; Ruby, Ruby on Rails, Python, MongoDB, and Elasticsearch on the backend; Kubernetes, Docker, and Terraform in infrastructure; GCP for cloud.
What you will love about Apollo
You will own the technical bets that define the company, work as a peer to engineering and product leadership, and have the scope and AI tooling to shape how a fast-moving organization builds. The listed Pay Range reflects the total cash compensation inclusive of annual base salary and annual bonus as applicable. For sales roles, the range provided is the role’s On Target Earnings ("OTE") range, meaning that the range includes both the sales commissions/sales bonus target and annual base salary for the role. This salary range may be inclusive of several career levels at Apollo and will be narrowed during the interview process based on a number of factors, including the candidate’s experience, qualifications, and location. Applicants interested in this role who are not located in the US may request the annual salary range for their location during the interview process.
Additional benefits for this role may include: equity; company bonus or sales commissions/bonuses; 401(k) plan; at least 10 paid holidays per year, flex PTO, and parental leave; employee assistance program and wellbeing benefits; global travel coverage; life/AD&D/STD/LTD insurance; FSA/HSA and medical, dental, and vision benefits.
San Francisco Pay Range
15,300 — $472,900 USDAbout Apollo
Apollo is the AI-powered go-to-market platform that helps revenue teams find, engage, and convert their best customers. We combine a database of more than 210 million contacts and 35 million companies with an agentic end-to-end GTM platform, and more than 500,000 companies rely on us to run their go-to-market motion. We are profitable, growing fast, and rebuilding the product around AI and agents.
Your role and mission
You will set technical direction at the level of the whole engineering organization. You will own the hardest, most ambiguous, and highest-stakes technical bets, the ones that shape the product for years, and you will be a force multiplier across many teams. Your judgment will be a reference point for how we build, and your impact will be felt org-wide rather than on any single team.
What you will do
• Own the technical direction of Apollo's most critical and most ambiguous problems, across team and organizational boundaries
• Make the architectural bets that shape the product and platform over multiple years, and be accountable for how they play out
• Set the technical strategy for the rebuild around AI and agents, and turn it into direction teams can execute
• Raise the engineering bar across the whole organization through the standards, patterns, and decisions you drive
• Multiply the output of engineers and teams far beyond your own code, through design, review, and mentorship of our most senior engineers
• Partner with engineering and product leadership as a peer on where the technology needs to go.
How we work: AI-native by default
You set the standard for what AI-native engineering looks like at the highest level. You use agents to move faster on the hardest design, investigation, and implementation work, you define the practices other engineers adopt, and you find the step-change bets where AI reshapes how we build the product, not just how fast we ship.
What we are looking for
• A track record of setting technical direction that shaped a product or platform across an entire engineering organization
• Depth across distributed systems and architecture, and command of the reliability, scale, and cost tradeoffs behind company-defining decisions
• The judgment to make the hardest calls under ambiguity, and the influence to align many teams behind them
• A record of multiplying the most senior engineers around you. Genuine, current fluency with AI-assisted development, and a clear point of view on where AI takes engineering next
Our tech stack
React on the front end; Ruby, Ruby on Rails, Python, MongoDB, and Elasticsearch on the backend; Kubernetes, Docker, and Terraform in infrastructure; GCP for cloud.
What you will love about Apollo
You will own the technical bets that define the company, work as a peer to engineering and product leadership, and have the scope and AI tooling to shape how a fast-moving organization builds. The listed Pay Range reflects the total cash compensation inclusive of annual base salary and annual bonus as applicable. For sales roles, the range provided is the role’s On Target Earnings ("OTE") range, meaning that the range includes both the sales commissions/sales bonus target and annual base salary for the role. This salary range may be inclusive of several career levels at Apollo and will be narrowed during the interview process based on a number of factors, including the candidate’s experience, qualifications, and location. Applicants interested in this role who are not located in the US may request the annual salary range for their location during the interview process.
Additional benefits for this role may include: equity; company bonus or sales commissions/bonuses; 401(k) plan; at least 10 paid holidays per year, flex PTO, and parental leave; employee assistance program and wellbeing benefits; global travel coverage; life/AD&D/STD/LTD insurance; FSA/HSA and medical, dental, and vision benefits.
San Francisco Pay Range
## 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!