Founding Senior Software Engineer

About Symphony

Symphony is building voice AI sims for large enterprises. Use cases include training front-line employees and augmenting & automating customer-facing workflows. 

Since launching in January, we’re live with 4 of the top 10 auto insurers in North America, helping train 1000s of newly hired claims adjusters using interactive voice AI simulations of real-world scenarios. Teams can create an infinite number of simulations allowing their teams to practice the job - avoiding costly mistakes with real customers.

We graduated from YCombinator’s F24 batch and are backed by top investors in Silicon Valley including 22 Ventures, Transpose Platform, and Rebel Fund. 

What you’ll do

• Take full ownership of new product features — from scoping and user experience design to implementation across the frontend, backend, database, and infrastructure layers
• Refine and test prompts and build new agentic features, researching novel approaches to improve reliability of LLM-based functionality
• Collaborate with founders to scope, plan, and prioritize new features
• Lead engineering best practices and code quality standards, leveraging AI coding tools to accelerate development and maintain technical excellence
• Work directly with enterprise customers—from sales and onboarding to implementation and ongoing support—to ensure successful adoption and feedback-driven iteration

You’ll enjoy this role if you:

• Are excited to experiment with new features as LLMs unlock product experiences that require rethinking traditional UI and workflows
• Enjoy thinking through new features end to end, including scalability, extensible abstractions, data model design, and long-term reliability
• Want extreme autonomy and ownership, including leading mission-critical initiatives from idea to execution
• Are ready to have a front-row seat at a high-growth startup, helping us craft our long-term vision, contributing to our GTM efforts, and pushing our hiring efforts

What a typical week might look like

• Use the latest AI coding tools to ship a critical feature end-to end
• Review user session recordings and feedback to find ways to improve our no-code role play builder
• Research and test advancements in the voice AI world, including new LLM and speech-to-text capabilities that can make AI roleplays more dynamic and human-like
• Build a custom prototype of a new feature to help push a sale
• Propose roadmap changes to the founders

What we’re looking for

• 3+ years of software engineering experience, owning end-to-end development efforts and leading technical decisions
• Experience across the stack, including frontend frameworks like React/Next.js, backend technologies like Node.js or Flask, relational databases, and/or infrastructure management
• High ownership - you’re not afraid to take accountability for large bodies of mission-critical work
• Strong verbal and written communication skills that enable crystal-clear, unambiguous collaboration with customers, teammates, and during technical discussions
• Opinionated about code quality and architectural decisions, with a bias toward maintainability, clarity, and long-term scalability
• Able to operate with minimal direction—proactively asking questions, doing your own research, and engaging others to resolve ambiguity

Bonus points

• Prior experience founding a software startup
• Built tools leveraging LLMs or ML in production
• Experience with real-time applications and technologies such as WebRTC, WebSockets, or streaming media pipelines
• Experience working on enterprise Saas applications