
AssemblyAI provides speech AI APIs that transcribe and extract insights from audio to make voice data searchable and actionable. The company delivers cloud-hosted speech-to-text and audio intelligence capabilities—including summarization, sentiment analysis, topic detection, content moderation, and PII redaction—via developer APIs and a no-code playground. Its technology stack centers on proprietary speech recognition models and LLM-based frameworks (e.g., LeMUR) for applying large language models to transcriptions. AssemblyAI operates as a B2B SaaS/API provider serving developers and companies such as CallRail, Fireflies, and Spotify. The platform targets voice-data use cases across contact centers, media, and analytics with integrations appropriate for product and developer workflows.

AssemblyAI provides speech AI APIs that transcribe and extract insights from audio to make voice data searchable and actionable. The company delivers cloud-hosted speech-to-text and audio intelligence capabilities—including summarization, sentiment analysis, topic detection, content moderation, and PII redaction—via developer APIs and a no-code playground. Its technology stack centers on proprietary speech recognition models and LLM-based frameworks (e.g., LeMUR) for applying large language models to transcriptions. AssemblyAI operates as a B2B SaaS/API provider serving developers and companies such as CallRail, Fireflies, and Spotify. The platform targets voice-data use cases across contact centers, media, and analytics with integrations appropriate for product and developer workflows.
What they do: Speech AI APIs for transcription and audio intelligence (summarization, sentiment, moderation, PII redaction, etc.)
Founded: 2017
HQ: San Francisco, CA
Total funding: ≈ $115M
Core customers: Developers and enterprises (examples: CallRail, Fireflies, Spotify)
Speech recognition and speech understanding for developers and enterprises across contact centers, media, and analytics.
2017
Software Development
$28M
Series A announced March 4, 2022 with participation from Y Combinator, John & Patrick Collison, Nat Friedman, and Daniel Gross
$30M
Series B announced July 14, 2022
$50M
December 4, 2023 round; brought disclosed total capital raised to roughly $115M
“Backed by top-tier VCs and notable angels (Accel, Insight Partners, Y Combinator, Nat Friedman, Daniel Gross, John Collison)”
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About AssemblyAI At AssemblyAI, we're building at the forefront of Speech AI, creating powerful models for speech-to-text and speech understanding available through a straightforward API. With more than 200,000 developers building on our API and over 5,000 paying customers, AssemblyAI is helping unlock and support the next generation of powerful, meaningful products built with AI.
Progress in AI is moving at an unprecedented pace– and our team is made up of experts in AI research that are focused on making sure that our customers are able to stay on the cutting edge, with production-ready AI models that are constantly updating and improving as our team continues to improve accuracy, latency, and what's possible with Speech AI. Our models consistently rank highest in industry benchmarks for accuracy, outperforming models from Google and Amazon, and up to 30% fewer hallucinations than OpenAI's Whisper. Our models power more than 2 billion end-user experiences each day, helping companies better understand customer feedback, run more productive meetings with automated meeting notes, and helping improve childhood literacy via ed tech tools.
We've raised funding by leading investors including Accel, Insight Partners, Y Combinator's AI Fund, Patrick and John Collision, Nat Friedman, and Daniel Gross. We're a remote team looking to build one of the next great AI companies, and are looking for driven, talented people to help us get there!
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
Drive Technical Execution
Elevate Engineering Standards
Build and Collaborate
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
What We're Looking For This role requires someone who is:
We're looking for the best person for this role - someone who can hit the ground running while growing with the team. The ideal candidate brings strong software engineering discipline, a passion for AI/LLMs, and genuine excitement about solving customer problems through reliable, thoughtfully designed infrastructure.
Pay Transparency: AssemblyAI strives to recruit and retain exceptional talent from diverse backgrounds while ensuring pay equity across our team. Our salary ranges are set to be competitive for our size, stage, and industry, and reflect just one component of the full compensation, benefits, and rewards we offer.
Salary determinations consider a variety of factors, including relevant experience, technical depth, skills demonstrated during the interview process, and maintaining internal equity with peers on the team. The range shared below represents a general expectation for the posted position. However, we are open to considering candidates who may fall above or below the outlined experience level—in those cases, we will communicate any adjustments to the expected salary range.
The range provided applies to candidates located in the United States . For candidates outside of the U.S., compensation ranges may differ; any adjustments will be communicated throughout the interview process.
Salary range: $180,000 - $240,000 The expected base compensation for this role is listed above. Our total compensation package includes competitive equity grants, 100% employer-paid benefits, and the flexibility of being fully remote.
Working at AssemblyAI We are a small but mighty group of startup veterans and experienced AI researchers with over 20 years of expertise in Machine Learning, Speech Recognition, and NLP. As a fully remote team, we're looking for people to join our team who are ambitious, curious, and lead with integrity. We're still in the early days of AI and of AssemblyAI's journey, and are looking for teammates who won't just fit in, but will help us define and build our company culture.
We're committed to creating a space where our employees can bring their full selves to work and have equal opportunity to succeed. No matter your race, gender identity or expression, sexual orientation, religion, origin, ability, age, veteran status, if joining this mission speaks to you, we encourage you to apply!
Using AI to Interview: If you're selected for an interview, please review this resource to better understand how AssemblyAI approaches the use of AI in our interview process.
Keep Exploring AssemblyAI:
Check us out on YouTube!
Learn more about AI models for speech recognition
Core Transcription | Audio Intelligence | LeMUR | Try the Playground
Our $50M Series C fundraise