Principal Software Engineer - C, Https, SSL

Principal Software Development Engineer

About Zscaler: Zscaler accelerates digital transformation so our customers can be more agile, efficient, resilient, and secure. Our cloud native Zero Trust Exchange platform protects thousands of customers from cyberattacks and data loss by securely connecting users, devices, and applications in any location. Here, impact in your role matters more than title and trust is built on results. We believe in transparency and value constructive, honest debate—we're focused on getting to the best ideas, faster. We build high-performing teams that can make an impact quickly and with high quality. To do this, we are building a culture of execution centered on customer obsession, collaboration, ownership, and accountability. We value high-impact, high-accountability with a sense of urgency where you're enabled to do your best work and embrace your potential. If you're driven by purpose, thrive on solving complex challenges and want to make a positive difference on a global scale, we invite you to bring your talents to Zscaler and help shape the future of cybersecurity.

Our Engineering team built the world's largest cloud security platform from the ground up, and we keep building. With more than 100 patents and big plans for enhancing services and increasing our global footprint, the team has made us and our multitenant architecture today's cloud security leader, with more than 15 million users in 185 countries. Bring your vision and passion to our team of cloud architects, software engineers, security experts, and more who are enabling organizations worldwide to harness speed and agility with a cloud-first strategy. We're looking for an experienced Principal Software Development Engineer to join our ZIA team. You will drive technical strategy, set engineering standards, mentor other engineers, and collaborate with Operations and Support to ensure a healthy cloud and exceptional customer outcomes. You'll demonstrate ownership, accountability, and a bias for precision in execution. This is a hybrid role, going into the San Jose, CA office 3 days a week.

Reporting to the Senior Director of Software Engineering, you'll be responsible for:

• Designing, implementing, and optimizing high-performance network applications and protocols using C and Python
• Architecting and scaling distributed systems across multiple data centers with stringent performance, resiliency, and multi-tenant requirements
• Working within Linux environments to perform system programming, scripting, and troubleshooting
• Contributing to and guiding key domains including post-quantum cryptography, Network Detection & Response (NDR), Zscaler Digital Experience (ZDX), and Zscaler OS
• Collaborating with teams to define requirements, design architectures, and ensure reliable software through testing and debugging

What We're Looking For (Minimum Qualifications):

• 10+ years of hands-on C programming experience on Unix/FreeBSD/Linux in distributed, enterprise-scale environments

• Proven expertise in high availability design, failover redundancy, load balancing, and performance optimization, with strong familiarity in SLOs, observability, and capacity planning for 24×7 services

• Deep understanding of networking protocols and services: DNS, HTTP/2, QUIC, TCP/IP, and SSL/TLS

• Experience with security technologies (firewall, IPS, authentication) and networking technologies (VPN/IPSec, data-plane traffic forwarding)

• Proficiency in troubleshooting network issues using tools such as Wireshark, tcpdump, curl, and wget

What Will Make You Stand Out (Preferred Qualifications):

• Experience with Python, Go, or Rust for systems and network programming

• Track record of staying current with industry trends and proposing improvements to reliability, scalability, and network efficiency

• Proficiency with AI code-assistance tools (e.g., Windsurf, Cursor, GCA, Claude) to accelerate development, refactoring, unit testing, and troubleshooting

Zscaler's salary ranges are benchmarked and are determined by role and level. The range displayed on each job posting reflects the minimum and maximum target for new hire salaries for the position across all US locations and could be higher or lower based on a multitude of factors, including job-related skills, experience, and relevant education or training. The base salary range listed for this full-time position excludes commission/bonus/equity (if applicable) + benefits.

Base Pay Range $182,000—$260,000 USD