Senior Software Engineer

Simpson Thacher & Bartlett LLP is a law firm seeking a Senior Software Engineer to support its Knowledge & Innovation department. The role designs, builds, and operates full-stack software, engineering infrastructure, and AI-powered legal technology solutions while collaborating with attorneys, data scientists, and other professionals.

Responsibilities:

• Design, develop, and maintain custom software solutions supporting Knowledge & Innovation initiatives, including AI-powered tools, internal platforms, and integrations with existing Firm systems
• Contribute to architectural decisions in partnership with the Director of Engineering, bringing practical perspective on tradeoffs between speed, reliability, and maintainability
• Build and extend integrations across SaaS platforms, internal systems, data sources, and AI/LLM services used in legal workflows
• Develop frontend experiences that are polished, consistent, and designed with care — including establishing and maintaining component libraries and design system foundations as the team's product surface grows
• Own and evolve the team's engineering infrastructure: CI/CD pipelines, deployment automation, infrastructure-as-code, and development environment tooling
• Establish observability practices — monitoring, logging, alerting — so the team has confidence in the health and behavior of production systems
• Partner with IT to navigate the Firm's infrastructure environment, coordinating on security protocols, cloud resources, and deployment targets
• Ensure systems are reliable, secure, and aligned with Firmwide technology standards
• Contribute to the development of AI-powered tools — including retrieval-augmented systems, document analysis platforms, search tools, and workflow automation — working alongside product, data scientists, and the broader K&I team
• Help translate complex legal and business requirements into practical, well-engineered software, collaborating with attorneys, knowledge management professionals, and practice solutions managers
• Support adoption and iteration by interfacing directly with legal staff as needed — demoing tools, gathering feedback, and helping users get value from what the team builds
• Evaluate and prototype new tools, frameworks, and approaches that could improve how the team builds — bring experiments that work to the rest of the team
• Help establish the engineering culture of a new function — contribute to decisions about how the team works, not just what it builds

Requirements:

• Bachelor's degree in Computer Science or related working experience
• 7+ years of experience in software engineering, with demonstrated progression in scope and responsibility
• Strong full-stack skills across JavaScript/TypeScript, React, Node.js, and Python
• Experience with cloud infrastructure (AWS and/or Azure), infrastructure-as-code (Terraform/Bicep), and CI/CD pipelines (GitHub Actions or equivalent)
• Practical experience with AI/LLM integration in production systems, or strong aptitude and interest in developing it
• Experience with agentic coding tools (e.g., Claude Code, Cursor, Codex)
• Comfort working directly with non-technical stakeholders — able to demo work, gather feedback, and explain technical decisions clearly
• Strong engineering judgment — knows when to build and what not to build
• Comfort with ambiguity — can make progress with incomplete information and adjust as context develops
• Pragmatic craftsmanship — cares about the quality and polish of what ships, without over-engineering
• Curiosity and initiative — brings ideas, experiments, and improvements without being asked
• Clear communication with both technical and non-technical audiences
• Simpson Thacher will not sponsor applicants for work visas for this position
• Experience in legal technology, professional services, or other highly regulated environments
• Experience establishing observability and monitoring practices (logging, alerting, dashboards) for production systems
• Familiarity with design systems, component libraries, or frontend architecture patterns at the systems level
• Experience integrating and extending enterprise SaaS platforms