Senior / Lead Research Scientist - Serbia

About the Position

Senior / Lead Research Scientist - Serbia

Inworld is a research lab and inference provider focused on real-time AI for consumer-facing applications. We build first-party speech models, serve LLMs, and run the inference behind modular APIs designed for high-volume, real-time workloads.

Hundreds of millions of users interact with Inworld-powered apps every day, and we serve over 10 trillion LLM tokens per month. Our models and infrastructure support consumer applications across companions, healthcare, fitness, education, media, and more. Our work spans model research, real-time inference, large-scale serving infrastructure, and the APIs developers use to bring these capabilities into production.

We’ve raised more than $125M from Lightspeed Venture Partners, Section 32, Kleiner Perkins, Microsoft’s M12 venture fund, Founders Fund, Meta, Stanford, and others. Our technology has powered experiences from companies including NVIDIA, Microsoft Xbox, Niantic, Logitech Streamlabs, Wishroll, Little Umbrella, and Bible Chat. Inworld has also been recognized by CB Insights as one of the 100 most promising AI companies globally and named one of LinkedIn’s Top 10 Startups in the USA.

Responsibilities

• Contribute to the development and improvement of real-time AI models and infrastructure.
• Collaborate with cross-functional teams to bring AI capabilities into production.
• Engage in model research, real-time inference, and large-scale serving infrastructure projects.

Requirements

• Experience: Foundation models, training, new architectures, RL, reward modeling, scaling, evaluation, benchmarks, eval loops, quality measurement, LLM-as-judge, failure analysis, frontier topics, multimodal models, agents, tool use, test-time compute, world models.
• Education: PhD in ML/NLP or equivalent practical experience.
• Public Work: Non-trivial AI side projects, interdisciplinary experiments, open-source contributions.
• Full-Stack Research Ownership: Ability to frame questions, run experiments, write papers, and ship results.
• Language: Professional fluency in English (written and spoken).

Who Thrives Here

• Pathfinders: Comfortable picking a direction and building the map as you go.
• Full-Cycle Researchers: Believe research isn't finished until it’s shipped.
• First-Principles Engineers: Obsess over the why and question approaches for better solutions.
• Mission Owners: Thrive on deep context and understanding the fundamental logic behind decisions.

What Working Here Is Like

• We hand you unclear problems and expect you to make them clear.
• We value researchers who say "I don't know yet" and then design the experiment that finds out.
• We treat evaluation as a first-class research product.
• Impact comes before publications, though we support sharing work that moves the field forward.
• Your work should be visible.
• Flat structure, fast iterations, minimal process theater.

We Offer

• Opportunity to work on cutting-edge AI projects.
• Collaborative environment with a diverse team.
• Professional growth and development opportunities.

About the Company

Inworld is a research lab and inference provider focused on real-time AI for consumer-facing applications. We build first-party speech models, serve LLMs, and run the inference behind modular APIs designed for high-volume, real-time workloads.

We’ve raised more than $125M from Lightspeed Venture Partners, Section 32, Kleiner Perkins, Microsoft’s M12 venture fund, Founders Fund, Meta, Stanford, and others. Our technology has powered experiences from companies including NVIDIA, Microsoft Xbox, Niantic, Logitech Streamlabs, Wishroll, Little Umbrella, and Bible Chat. Inworld has also been recognized by CB Insights as one of the 100 most promising AI companies globally and named one of LinkedIn’s Top 10 Startups in the USA.