Software Engineer - Backend

About Billables

Billables AI is building the AI-powered operating layer for professional service firms, and we're starting where the pain is deepest: the legal industry. Our platform automates the manual overhead that slows lawyers down, bringing together intelligent timekeeping, work activity capture, and operational visibility so firms can understand how work happens and build a more efficient, profitable practice. The best work happens when people aren't buried in administrative burden, and that's exactly the problem we're solving.

Named Legal Tech Company of the Year by Law.com in 2026, Billables AI is one of the fastest-growing companies at the intersection of AI and legal technology. Our team brings together expert AI researchers and veteran startup builders who know how to move fast, build with conviction, and deliver software that sits at the core of how our customers work and generate revenue. Based in San Francisco, we empower everyone on the team to drive meaningful work end-to-end.

About the Role

We're looking for a mid-to-senior backend engineer to help build and scale the core systems behind our platform. You'll take problems from early idea to production: shaping requirements, making technical decisions, and working across teams to deliver the right outcome. You'll work closely with backend, frontend and AI engineers, and directly with leadership, go-to-market and customers.

You've shipped in a startup or another fast-moving environment, and you're comfortable turning a loosely defined problem into a spec, a plan and working software. This role is a great fit if you like owning meaningful parts of a system and making pragmatic trade-offs to ship.

No legal background needed. You'll pick up how law firms track and bill time (billing codes, LEDES, matter-level rules) on the job.

What You'll Work On

• Design, build and maintain backend services (Python, gRPC, Postgres, Redis)
• Build and own integrations with the systems our customers run on, including legal billing and practice management platforms, Microsoft 365, Zoom and others. Integrations are a big part of the work today, and the role will grow toward the core platform as it matures
• Scale the pipelines that turn high volumes of work activity (email, calendar, calls, chat, browser activity) into accurate time entries
• Own projects end to end: clarify requirements, propose solutions, implement, and iterate in production
• Build for enterprise requirements: security, tenant isolation, permissions, and data residency for firms handling privileged client data
• Improve reliability, performance and observability across services, and take part in an on-call rotation
• Balance roadmap work with the specific needs of large firm customers
• Contribute to system architecture and long-term technical direction
• Be willing to step outside your primary lane when needed, especially into frontend work, as well as infrastructure

What We're Looking For

• A strong track record of deploying and maintaining high-quality production code
• Proficiency in Python and strong backend fundamentals (APIs, data modeling, system design)
• Experience integrating with third-party APIs, including auth flows, rate limits and inconsistent data
• A high-ownership mindset: you take responsibility for outcomes, not just code
• Comfort moving quickly and making decisions without perfect information, ideally from experience at an early-stage company
• Active use of AI tools (LLMs, copilots, coding agents) in your day-to-day development
• Clear communication with both technical and non-technical stakeholders

Nice to Have

• Experience building and scaling distributed systems or microservice architectures
• Experience with gRPC or similar RPC frameworks
• Experience with DevOps and infrastructure (Docker, IaC, CI/CD)
• Experience working with AI/ML systems or integrating LLMs into products
• Some frontend experience (TypeScript, React) or a willingness to pick it up
• Experience with enterprise or regulated customers (security reviews, SOC 2, data residency)

What You Might Work On First

• Connecting Billables with the email, calendar and meeting tools firms already use, so a whole firm can be set up in one step
• Capturing more kinds of work activity, such as chat, and turning it into accurate time entries
• Helping new customers get value from day one by bringing in their historical data

Why This Role

• You'll work on systems that sit at the center of how our customers run their business and earn revenue
• You'll have real ownership early, not just implementation work