Senior Software Engineer - Activation APIs

Role Overview

Senior Software Engineer - Activation APIs at Yahoo. Build and optimize high-performance production APIs that enable real-time personalization and advertising systems to access large-scale user profile and audience data.

Responsibilities

• Develop and optimize REST and gRPC APIs for:
  • user profile activation
  • audience segment retrieval
  • enrichment data access
• Integrate API endpoints with downstream systems and applications while meeting sub-10ms p99 latency at millions of RPS
• Implement monitoring and alerting for latency, throughput, error rates, cache hit rates, and 99.99% availability SLAs
• Optimize data access patterns using Cloud Spanner plus Valkey (Redis) distributed caching
• Write unit, integration, and load tests and maintain API documentation using OpenAPI/Swagger
• Collaborate with Infrastructure on deployment, autoscaling, and production operations in GCP (Cloud Run, GKE)
• Participate in on-call, incident response, and production performance troubleshooting
• Implement authentication, authorization, rate limiting, and quota management for secure access to sensitive user data
• Profile and improve performance via query, caching, and serialization optimization
• Mentor junior engineers and contribute to API/code review and design discussions

Requirements

• 5+ years of software engineering experience
• Deep expertise in high-performance API development and production systems engineering

Nice-to-Haves

• Experience with distributed caching strategies and large-scale distributed systems
• Strong reliability practices (root cause analysis, preventing recurrence)