Staff ML Engineer - Voice AI

Toast is driven by building the restaurant platform that helps restaurants adapt, take control, and get back to what they do best: building the businesses they love.

Now, more than ever, the Toast team is committed to our customers. We’re taking steps to help restaurants navigate these unprecedented times with technology, resources, and community. Our focus is on building the restaurant platform that helps restaurants adapt, take control, and get back to what they do best: building the businesses they love. And because our technology is purpose-built for restaurants, by restaurant people, restaurants can trust that we’ll deliver on their needs for today while investing in experiences that will power their restaurant of the future. 

Bready* to make a change?

Toast is looking for a Staff Machine Learning Engineer to bring Voice AI capabilities into the Toast platform. You will work with engineers, data scientists and product managers to turn Voice AI solutions into business impact across product lines, including phone ordering, Toast Local app, drive thru, kiosk and menu recommendations. We need your help to create the Voice AI capabilities and infrastructure that enables our data scientists and product engineers to build, release, and monitor models at scale.

About this roll* (Responsibilities):

• Apply Voice AI expertise to help further define and improve the capabilities of Toast’s product platform
• Design APIs and inference services to support voice interactions across Toast platforms and devices.
• Work closely with product teams to translate use cases into natural, efficient, and emotionally resonant voice interactions.
• Lead model optimization efforts for latency, memory, and inference cost — including edge and mobile deployment if applicable.
• Collaborate with data scientists and ML engineers to prototype and productionize new ideas in generative speech, multilingual processing, and agentic behavior.
• Mentor junior engineers and contribute to fostering a culture of technical excellence.

Do you have the right ingredients*? (Requirements):

• Bachelor’s or Master’s degree in Computer Science, AI, Machine Learning, or related field.
• 7+ years of ML software development experience with hands-on experience in voice AI, speech processing, or conversational AI systems.
• A proven track record of shipping Agentic Voice AI solutions in production at scale.
• Deep expertise in automatic speech recognition (ASR), text-to-speech (TTS), and speech-to-speech (S2S) model development and evaluation and voice agent systems.
• Familiarity with voice AI toolkits such as Whisper, Koruru TTS, Hugging Face Transformers, or OpenAI Realtime API.
• Extensive background in voice AI technologies is required, with demonstrated expertise in toolkits such as Whisper, ESPNet, Koruru TTS, Hugging Face Transformers, and OpenAI Realtime API.
• Strong background in machine learning and signal processing.
• Proficiency in Python, Java/Kotlin and SQL and experience with ML frameworks like PyTorch or TensorFlow.
• Experience in software engineering best practices and tools including object-oriented programming, test-driven development, CI/CD, git, shell scripting, task orchestration (Airflow)
• Experience with microservice-based architecture, preferably with AWS tooling (SageMaker, DynamoDB, Athena, etc.)
• Strong communication skills, with a track record of technical leadership and cross-functional collaboration.

Special Sauce* (Nice to Haves):

• Experience with real-time speech systems, including streaming ASR or low-latency TTS/S2S.
• Familiarity with open-source speech toolkits: Kokoro TTS, ESPnet, Fairseq, OpenAI Whisper, or equivalent.
• Experience building interactive, embodied, or voice-based agents using LLMs or hybrid architectures.
• Background in deploying models to edge/mobile environments or with hardware acceleration.

Our Spread* of Total Rewards
We strive to provide competitive compensation and benefits programs that help to attract, retain, and motivate the best and brightest people in our industry. Our total rewards package goes beyond great earnings potential and provides the means to a healthy lifestyle with the flexibility to meet Toasters’ changing needs. Learn more about our benefits at https://careers.toasttab.com/toast-benefits.

*Bread puns encouraged but not required

The base salary range for this role is listed below. The starting salary will be determined based on skills and experience.