Senior Software Engineer - Backend Systems

About Valency Valency Systems is a small, dynamic team of engineers, scientists, and researchers building the global hub for the agentic research era. We're based in Berkeley, California, and we're building something that matters. If you care about open science, advancing research at the speed of thought, and using AI to accelerate discovery, we'd love to talk. Our team is hybrid. We come together in person 3 days a week, with the option for 2 days of remote work. About the Role We're looking for a Senior Software Engineer who will report to the Head of Engineering. This person thrives deep in the codebase, raises the bar for everyone around them, and ships work that stands the test of time. You'll be a trusted voice in architectural decisions, a go-to resource for hard problems, and a mentor to the engineers around you, all while staying deeply hands-on. Your foundation is backend systems: designing APIs people love to work with, building infrastructure that doesn't wake anyone up at 3am, and making data models that make sense six months later. You know how to make thoughtful trade-offs under pressure, and you leave every system better than you found it. What You'll Do Backend Engineering • Design, build, and own critical backend services — APIs, data pipelines, async workers, and the infrastructure that keeps them running reliably at scale • Make sound architectural decisions and document trade-offs clearly so the whole team can learn from them • Drive platform and reliability investments alongside feature work — the foundational improvements that keep pace with growth • Establish and uphold high standards for code quality, test coverage, and operational excellence • Diagnose and resolve complex performance, reliability, and scalability issues; conduct thorough post-mortems that prevent recurrence Distributed Systems & Infrastructure • Design and maintain distributed systems that are resilient to failure — applying patterns like circuit breakers, retries, idempotency, and rate limiting where they count • Own the full lifecycle of services from design through deployment, including CI/CD pipelines, containerization (Docker/Kubernetes), and cloud infrastructure • Implement and iterate on observability practices: structured logging, metrics dashboards, distributed tracing, and alerting • Contribute to infrastructure-as-code practices (Terraform, Pulumi, or similar) and cloud cost optimization Data & Integrations • Design performant, well-normalized data models across relational (PostgreSQL, MySQL) and non-relational (Redis, MongoDB, DynamoDB) stores • Build and maintain data pipelines, ETL/ELT workflows, and integrations with third-party services and external APIs • Apply caching strategies thoughtfully — CDN, in-memory, and application-level — and understand the failure modes of each • Work with message queues and event streaming platforms (Kafka, SQS, RabbitMQ) to build decoupled, async architectures Security & Compliance • Apply secure coding practices by default: input validation, secrets management, least-privilege access, and protection against common vulnerabilities • Contribute to compliance efforts (SOC 2, GDPR, or similar) with an understanding of how engineering decisions affect data privacy and auditability Technical Leadership • Be the go-to engineer for hard problems — unblock teammates, provide crisp technical direction, and raise the quality of design reviews • Mentor junior and mid-level engineers through code review, pairing, and direct, constructive feedback • Write architecture decision records (ADRs) and technical documentation that outlast the original project • Partner with Product and Design to scope work realistically, surface constraints early, and deliver with clarity • Represent engineering in cross-functional conversations and earn influence through execution, not hierarchy What We're Looking For Required • 8+ years of software engineering experience, with deep expertise in backend systems — APIs, databases, distributed architectures, and cloud infrastructure • Strong command of at least one backend language (Python, Go, Java, Rust, or similar) and comfort working across major cloud platforms (AWS, GCP, or Azure) • Hands-on experience with relational databases (schema design, query optimization, indexing) and familiarity with non-relational or caching layers • Experience with containerization and orchestration (Docker, Kubernetes) and CI/CD pipelines • Demonstrated ability to own and deliver complex, ambiguous projects end-to-end with minimal supervision • Track record of mentoring engineers and influencing technical direction without formal authority • Clear, direct communication — you can explain a hard trade-off to an engineer and a product manager alike Nice to Have • Experience working in a startup environment — you've built and scaled systems while the business was growing rapidly underneath them, worn multiple hats, and thrived in ambiguity • Experience with our stack or adjacent: Node.js/TypeScript, AWS Lambda/CDK/Step Functions, PostgreSQL, Cloudflare • Familiarity with auth systems (e.g. OAuth) and observability tooling • Experience with workflow orchestration tools (Temporal, Airflow, Prefect) and async job processing at scale • Working knowledge of infrastructure-as-code (Terraform, Pulumi) and cloud cost management What Makes Someone Exceptional Here This role rewards engineers who think in systems — who aren't satisfied shipping a feature that works today if it'll break at 10x scale. You're someone who: • Has deep backend instincts: clean data models, well-designed APIs, observable services, and resilient failure modes • Leaves code, documentation, and systems measurably better than you found them • Brings a product mindset: you understand why you're building something, not just how • Earns trust through execution, not hierarchy — your opinion carries weight because of what you've shipped • Thrives in the ambiguity of a fast-moving company and knows when to move fast vs. when to slow down and get it right • Could step into a management role if needed, but genuinely prefers to stay in the code and go deeper Why Join Us • Meaningful backend challenges on a product that's growing fast and reaching real users • A small, high-trust team where your decisions have outsized impact • A culture that values engineering excellence and invests seriously in the people who drive it Compensation, Benefits & Equity We offer a competitive salary, benefits, and meaningful equity in a company building something important from the ground up. Work Authorization Candidates must be legally authorized to work in the United States.