About AssemblyAI
AssemblyAI builds the best-in-class Speech AI models powering the next generation of voice applications. Our models serve 600M+ inference calls monthly, process 1M+ hours of audio daily, and power 2 billion+ end-user experiences—from voice agents and meeting assistants to contact centers and medical scribes. Companies like Zoom, Granola, Fireflies, Cluely, and Calabrio rely on AssemblyAI to ship production-ready voice AI.
We're at an inflection point in Speech AI. We released Universal-Streaming in mid-2025, and it has quickly earned its place as the model offering the best accuracy-latency-cost tradeoff on the market. Our research team drives these advances and ships with relentless velocity. Since releasing Universal-Streaming, we've already launched keyterms prompting feature and multilingual support—with more significant improvements on the roadmap.
We've raised $115M+ from Accel, Insight Partners, Y Combinator's AI Fund, Patrick and John Collison, Nat Friedman, and Daniel Gross. We're a remote team building one of the next great AI companies—and we're looking for researchers who will shape its future.
About the Role
We're seeking an exceptional Senior Software Engineer to join our LLM team. This role is focused on building and maintaining our LLM gateway service—a unified API platform that connects customers to multiple LLM providers. You'll work on high-impact projects that directly solve customer problems, improve their AI and agentic workflows, and ensure reliable access to the best models for their use cases.
This is a deeply customer-focused role. You'll work closely with our customer success team to understand customer challenges, help optimize their prompt strategies, build features that address their pain points, and ensure our service reliably delivers value. We're looking for someone who combines software engineering excellence with genuine curiosity about how customers use AI and a drive to make their lives better.
As a Senior Engineer, you'll drive technical execution within the team, taking ownership of significant features and integrations while mentoring more junior engineers. You should be passionate about writing clean, maintainable code, implementing comprehensive testing strategies, and building highly reliable systems in service of solving real customer problems.
This role requires close collaboration with customer success, product managers, external API providers, and other engineering stakeholders. You'll need to balance technical excellence with pragmatic delivery in a fast-paced startup environment where uptime, reliability, and customer success are critical.
What You'll Do
Solve Customer Problems
- Partner closely with the customer success team to understand customer use cases, challenges, and integration needs
- Translate customer pain points surfaced by the CS team into technical solutions and product improvements
- Build features and tooling that directly address customer needs and improve their workflows
- Provide technical guidance and expertise to the customer success team to help them support customers effectively
Drive Technical Execution
- Own and deliver complete features and integrations within our LLM gateway service
- Build and maintain integrations with multiple LLM providers and AI services (OpenAI, Anthropic, Google Vertex, AWS Bedrock etc.)
- Write clean, maintainable, well-tested code following best practices
- Design and implement scalable, fault-tolerant solutions with appropriate abstractions
- Proactively identify and address technical debt, reliability issues, and code quality concerns
- Participate in on-call rotation to ensure service reliability and rapid incident response
Elevate Engineering Standards
- Conduct thorough code reviews focused on maintainability, testing, reliability, and architectural concerns
- Ensure proper test coverage across unit, integration, and end-to-end testing levels
- Improve code maintainability and extensibility through targeted refactoring
- Contribute to runbooks, incident postmortems, customer-facing documentation, and knowledge sharing
- Identify bottlenecks and propose solutions to improve team velocity and system reliability
Build and Collaborate
- Work closely with product, customer success, and engineering teams to deliver solutions
- Collaborate with external API providers to troubleshoot integration issues and improve reliability
- Translate ambiguous customer requirements into well-scoped technical work
- Proactively communicate status, risks, and blockers
- Mentor junior engineers on coding standards, reliability practices, and customer-centric thinking
- Participate in architectural discussions and contribute to technical decisions
What You'll Need
Core Requirements
- 5+ years of professional software engineering experience
- Strong proficiency in Go with demonstrated ability to write production-quality code
- Hands-on experience with LLM APIs (OpenAI, Anthropic, etc.) and understanding of prompt engineering concepts
- Experience building or working with API gateways, proxies, and rate limiting systems
- Deep experience with prompt engineering, chain-of-thought, few-shot learning, and other LLM optimization techniques
- Experience building applications with llms or ai agents with cascading architectures
- Solid understanding of software engineering fundamentals:
- Data structures and algorithms
- System design and architectural patterns
- Testing strategies (unit, integration, end-to-end)
- Code review practices and technical collaboration
- Experience with:
- RESTful APIs and distributed systems concepts
- Building or integrating with third-party APIs
- SQL and database design
- Version control (Git) and CI/CD pipelines
- Containerization (Docker) and cloud infrastructure
- Strong communication skills and ability to collaborate effectively with cross-functional teams
- Track record of delivering high-quality, reliable software in a fast-paced, team environment
- Ability to thrive in a startup environment with changing priorities and rapid iteration
Nice to Haves
- Experience with AWS services (ECS, Lambda, ElastiCache/Redis, RDS, S3, CloudWatch, API Gateway)
- Experience with monitoring and observability tools (Datadog, CloudWatch)
- Experience with request routing, load balancing, and traffic management
- Experience with circuit breakers, retry logic, fallback strategies, and fault tolerance patterns
- Understanding of API design, versioning, and backward compatibility
- Experience working closely with customer success or support teams
What We're Looking For
This role requires someone who is:
- Customer-obsessed - You genuinely care about solving customer problems and making their lives easier, working through the customer success team to understand and address their needs
- Excellent at software fundamentals - You write code that others want to emulate
- Quality-focused - You care deeply about testing, documentation, and maintainability
- Reliability-obsessed - You understand that uptime and performance directly impact customer trust
- LLM-savvy - You understand prompt engineering, model capabilities, and how to help customers get the best results
- Integration-savvy - You've wrestled with third-party APIs and know how to build resilient integrations
- Collaborative - You work well with diverse stakeholders and partner effectively with customer success teams
- Communicative - You can explain complex technical concepts clearly to teammates and cross-functional partners