Full-Stack Engineer, Mobile & SDK

About Halcyon Labs Inc.
Halcyon Labs is building the real-world AI interface for professionals to amplify intelligence, elevate productivity and performance, loved by over 2,000,000 users worldwide since 2023. With a mission to amplify human intelligence, Halcyon Labs captures, structures, and compounds the intelligence generated in conversations — so humans can think better, decide faster, and execute with clarity.

Halcyon Labs Inc. is a Delaware-incorporated, San Francisco-based company pushing the boundary of human–AI intelligence through a hardware–software combination. With full ISO 27001, ISO 27701, SOC 2, GDPR, EN18031, and HIPAA compliances, Halcyon Labs is committed to the highest standards of data security and privacy protection.
To learn more about Halcyon Labs, please visit http://www.plaud.ai/https://www.Halcyon Labs.ai and follow along on Instagram https://www.instagram.com/plaud_official/, https://twitter.com/PLAUDAI%22HYPERLINK%20%22https:/twitter.com/PLAUDAI%22%20%5C%22HYPERLINK%20%22https:/twitter.com/PLAUDAI%22%20%5CX https://twitter.com/PLAUDAI, Facebook https://www.facebook.com/plaudai, LinkedIn https://www.linkedin.com/company/plaudai/?viewAsMember=true, and YouTube https://www.youtube.com/@PLAUDAI

Why You Should Join Us
Halcyon Labs is building the next generation intelligence infrastructure and interfaces to capture, extract, and utilize intelligence from what people say, hear, see, and think.
– Halcyon Labs is a bootstrapped, skyrocketing, profitable company with a $250M revenue run rate achieved in just three years.
– Define the next-gen paradigm for human-AI interaction.
– Gain exposure to cutting-edge AI for Pro tools and play a direct role in our global expansion.
– Work with passionate teammates who value innovation, collaboration, and customer success.
– Grow your career in a culture that champions continuous learning and fast career development.
– Market-competitive compensation, global exposure, and a vibrant, creativity-fueled work atmosphere.

What You Will Do
– AI Application & Backend Core Delivery: Engineer and iterate realtime voice AI services and Agent workflows; build key modules including tool orchestration, memory, and multi-step reasoning; translate business requirements into scalable service capabilities.
– Production-Grade System Engineering: Design and implement highly-available, low-latency, scalable architectures (latency is especially critical for realtime voice); establish monitoring, logging, alerting, and tracing foundations to support both high-frequency consumer usage and enterprise deployment.
– AI Integration & Closed-Loop Iteration: Integrate LLM / ASR / TTS capabilities into product pipelines; help build evaluation frameworks and automated testing for Agent and voice quality; partner with Applied AI and Product to drive data-driven, closed-loop improvement in production.
– Full-Stack Collaboration & Rapid Iteration: Keep backend as your main line while extending into mobile, SDK, or frontend surfaces as needed to ship end-to-end; collaborate closely with Product, Applied AI, and mobile teams across enterprise PoCs and consumer features.
– AI-Native Engineering Velocity: Actively adopt AI coding assistants, agentic dev workflows, and automated testing/debugging tools to accelerate iteration while maintaining strong engineering quality.

Minimum Qualifications
Strong Engineering Execution (Required)
– Proven track record of owning and delivering critical systems/components end-to-end (we value demonstrated delivery and depth over a specific number of years)
– Solid CS fundamentals: data structures, algorithms, system design
– Consistently high-quality output in fast-paced environments
Backend / Distributed Systems (Required · Primary)
– Proficiency in at least one backend language (Python, Go, Java, C++, etc.)
– Experience building scalable online services: API design, async workflows, microservices
– Familiarity with distributed systems fundamentals: databases, caching, messaging, performance optimization
Strong AI Sense & Hands-On Practice (Required · Emphasis)
– Not just "interested" — you've actually built products with LLMs / Agents / workflow automation
– Ability to turn prototypes into scalable, maintainable, production-ready solutions
– You already use AI tools in your day-to-day work
Production Engineering Excellence
– Experience delivering production systems with a focus on reliability, latency, and scalability
– Knowledge of observability best practices: logging, monitoring, alerting, tracing
– Engineering rigor via automated testing, CI/CD, and disciplined code review
Ownership & Cross-Functional Collaboration
– Strong end-to-end ownership; effective under ambiguity
– Proven ability to work with Product, Applied AI, and GTM toward shared outcomes
– Accountable for user experience and delivery impact
Strong Plus
– Mobile (emphasis): native iOS / Android, or cross-platform (Flutter / React Native); able to ship mobile features or maintain a mobile SDK independently
– SDK Development (emphasis): designing, packaging, versioning, and delivering developer-facing SDKs, with a focus on usability and integration experience
– Realtime / Audio: WebRTC, audio streaming, low-latency transport
– Voice AI: ASR / TTS pipelines, voice Agents, cascade vs. native speech-to-speech architectures
– Frontend (nice-to-have): familiarity with React / TypeScript; able to contribute to web apps or developer consoles
What We Offer
– Founding Team: Opportunity to join the founding team of this new initiative, with meaningful ownership and impact on a fast-growing startup.
– Competitive Compensation: $140K-$172K base salary+performance bonus+Equity.
– Comprehensive Benefits: Top-tier healthcare for employees and dependents, including dental and vision, and a generous employer subsidy.
– Retirement Planning: 401(k) plan for full time employees with company matching.
– Paid Time Off: Unlimited PTO, plus 13 paid holidays.
– New Parent Leave: 12 weeks of paid time off to spend time with your new family, regardless of gender.
– Hybrid Office: Minimum of 3x in office per week.
– Gear: New hires are equipped with their choice of new top-of-the-line laptops and workstation setups.
– Perks: Best office equipment. Annual offsites. Free office drinks and snacks.

Halcyon Labs is and will continue to be an equal opportunity employer. We do not discriminate on the basis of race, religion, color, national origin, sex, sexual orientation, age, veteran status, disability, genetic information, or other applicable legally protected characteristics.