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Senior Software Engineer - Appsec

  • Boston, MA
  • Engineering

At Klaviyo, we value the unique backgrounds, experiences and perspectives each Klaviyo (we call ourselves Klaviyos) brings to our workplace each and every day. We believe everyone deserves a fair shot at success and appreciate the experiences each person brings beyond the traditional job requirements. If you’re a close but not exact match with the description, we hope you’ll still consider applying. Want to learn more about life at Klaviyo? Visit to see how we empower creators to own their own destiny.

About the team

The mission of the Application Security (AppSec) team is to provide best in class tooling for account management, authentication, authorization, and data security and integrity to protect the data of our 250,000+ customers and the data they own across their ecosystem. 

The Appsec team focuses on the backend development and service architecture for our authentication & authorization services, including identity and access management, logging and auditing, single sign-on, and role based access policies. Along with the services, we own the frontend experience for these features and bring a customer-focused approach to balancing customer ease of use and clear user experiences with each security feature we release. 

About the role

As a Senior Software Engineer, you will be responsible for the ownership of key features within the security space, working alongside other experienced engineers and mentoring junior engineers. You will work directly with the team and our product manager to help drive technical conclusions from stakeholders, as well as set our roadmap, team objectives, and goals.

How you’ll make an impact

  • Mentor and pair with other Klaviyo engineers to build better software by focusing on performance, self-healing systems, configuration as code, defensive programming, application security, etc.
  • Prototype and advocate for architectural improvements to achieve breakthrough results in Klaviyo systems’ operational scalability and reliability
  • Design and develop systems and processes that continually increase velocity within the team and our areas of ownership
  • Champion best practices by actively collaborating with other teams in a culture that values whiteboarding and technical design review
  • Work hand-in-hand with customer facing roles such as our sales and support teams, along with the teams Product Manager, to ship high value features.
  • Confidently make informed, data-driven decisions in a fast paced environment with competing priorities

What we’re looking for

  • 5+ years of experience developing software in a modern language such as: JavaScript, Python, Java, Go, Ruby, TypeScript, Java, C, C++, C#, etc
  • Knowledge and understanding of monolithic and microservices architectures
  • Cloud development utilizing a major provider such as AWS, GCE, Azure, etc.
  • Good communication skills
  • Ability to participate in an on-call rotation

Nice to haves

  • Previous experience in a relevant security focused product or company 
  • Experience working with common identity provider vendors, building authorization and authentication features or platforms.
  • Experience leading projects across multiple teams or quarters
  • Experience with Kubernetes
  • Receptive to feedback, Klaviyos are what we create together.

Get to Know Klaviyo

We’re Klaviyo (pronounced clay-vee-oh). We empower creators to own their destiny by making first-party data accessible and actionable like never before. We see limitless potential for the technology we’re developing to nurture personalized experiences in ecommerce and beyond. To reach our goals, we need our own crew of remarkable creators—ambitious and collaborative teammates who stay focused on our north star: delighting our customers. If you’re ready to do the best work of your career, where you’ll be welcomed as your whole self from day one and supported with generous benefits, we hope you’ll join us.

Upon request, you can receive additional information about the compensation and benefits for this role. Requests can be submitted here . Additional information regarding benefits can be found at .

Klaviyo is committed to a policy of equal opportunity and non-discrimination. We do not discriminate on the basis of race, ethnicity, citizenship, national origin, color, religion or religious creed, age, sex (including pregnancy), gender identity, sexual orientation, physical or mental disability, veteran or active military status, marital status, criminal record, genetics, retaliation, sexual harassment or any other characteristic protected by applicable law.

You can find our Job Applicant Privacy Notice here .

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