Software Engineer, Core Services

SOFTWARE ENGINEER, CORE SERVICES

As a Software Engineer on the Core Services team at SpaceXSI, you'll own the critical shared services that sit between our product surfaces and the infrastructure layer: auth, webhooks, and the backend systems that power agent workflows. SpaceXSI is redefining how developers write code, and your work is what makes that possible at scale. You'll build the systems that every product team depends on, ensuring they are reliable, well-abstracted, and ready for whatever comes next.

RESPONSIBILITIES

• Own authentication: designing and implementing a scalable auth architecture that secures one of the most widely-used developer tools in the world
• Powering the agent backend: owning the infrastructure behind Cursor's agent workflows, optimizing for end-to-end performance and reliability as agents become central to the developer experience
• Build a robust webhook server: handling high-throughput event delivery with proper retry semantics, dead-letter queues, and observability so external integrations just work
• Harden SCM integrations: building resilient abstractions over source control providers so Cursor stays rock-solid regardless of third-party conditions
• Drive end-to-end agent reliability: partnering with the client and inference teams to improve the full path from user action to agent response, closing the loop on one of the hardest problems in AI-powered development

BASIC

QUALIFICATIONS

• Experience building and operating backend services in production. Experience working with APIs and third-party integrations.

PREFERRED SKILLS AND

EXPERIENCE

• Experience with auth systems, API gateways, or webhook infrastructure
• Experience working on agentic products or infrastructure and strong opinions on reliability and performance of complex multi-step systems
• Care deeply about clean abstractions, well-defined service contracts, and making it easy for other engineers to build on top of your work
• Strong software engineering fundamentals and enjoying owning the full lifecycle of production services
• Experience with authentication/authorization frameworks (OAuth, JWTs, RBAC), event-driven architectures, or building developer-facing platform services is a plus

ADDITIONAL

REQUIREMENTS

• If there appears to be a fit, we'll reach out to schedule 2-3 short technicals. After, we'll schedule an onsite in our office, where you'll work on a small project, discuss ideas, and meet the team

Annual Salary

$140,000 - $225,000 USD