Senior Software Engineer - Activation APIs

Yahoo is a leading technology company connecting brands and partners with a vast audience. The Senior Software Engineer will build and optimize high-performance APIs that are critical for personalization and advertising systems, impacting user experience and revenue.

Responsibilities:

• Develop and optimize high-performance REST and gRPC APIs for user profile activation, audience segment retrieval, and enrichment data access
• Implement API endpoints integrating with downstream systems and applications, ensuring sub-10ms p99 latency at millions of RPS
• Build comprehensive monitoring and alerting systems tracking API latency, throughput, error rates, cache hit rates, and SLA compliance (99.99% availability)
• Optimize data access patterns using Cloud Spanner and Valkey (Redis) distributed caching for ultra-low-latency response times
• Write extensive unit tests, integration tests, load tests, and API documentation following OpenAPI/Swagger specifications
• Collaborate with Infrastructure teams on API deployment strategies, autoscaling policies, and production operations in GCP (Cloud Run, GKE)
• Participate in on-call rotation supporting production API availability, incident response, and performance troubleshooting
• Implement API authentication, authorization, rate limiting, and quota management ensuring secure access to sensitive user data
• Improve API efficiency through profiling, performance analysis, and optimization of database queries, caching strategies, and serialization
• Mentor junior engineers on API design patterns, production best practices, and distributed systems principles
• Troubleshoot production incidents, perform root cause analysis, and implement reliability improvements to prevent recurrence
• Contribute to API design reviews, code reviews, and technical discussions improving team practices and code quality

Requirements:

• Bachelor's degree in Computer Science, Engineering, or related technical field
• 5+ years software engineering experience building production systems
• 3+ years hands-on experience developing and operating high-performance APIs or distributed services
• Proven track record delivering high-quality, well-tested code on schedule
• Strong proficiency in Java, Python, or Go for backend API development
• Hands-on experience with REST API design, gRPC, authentication (OAuth 2.0, JWT), and rate limiting
• Experience with Google Cloud Platform: Cloud Run, GKE, Cloud Spanner, Memorystore (Redis), Cloud Load Balancing, or AWS equivalents
• Understanding of distributed systems principles: caching strategies, load balancing, database optimization, fault tolerance
• SQL proficiency and experience with distributed databases (Spanner, CockroachDB, TiDB) or relational databases at scale
• Familiarity with API monitoring and observability: metrics, logs, traces, SLIs/SLOs, error budgets
• Demonstrated ability delivering well-scoped technical solutions on schedule with minimal guidance
• Strong problem-solving and debugging skills in production environments
• Excellent collaboration and communication abilities working with cross-functional teams
• Team-level impact with ability to influence technical decisions within immediate team
• Understanding of data privacy compliance (GDPR, CCPA) in API design and implementation
• Experience with Cloud Spanner, Valkey/Redis, or other low-latency data stores in production
• Knowledge of API gateways (Apigee, Kong, Ambassador) and service mesh (Istio, Linkerd)
• Prior experience in adtech, audience platforms, or high-scale consumer services (millions of RPS)
• Understanding of privacy compliance requirements (GDPR, CCPA) and secure API design patterns
• Familiarity with OpenAPI/Swagger specifications, API testing frameworks (Postman, k6, Locust)
• Experience with chaos engineering, load testing, and performance benchmarking
• Contributions to open-source projects, technical blogging, or API design communities
• Self-driven, detail-oriented, excellent multitasking abilities in fast-paced environments