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hillclimb

YC F25

San Francisco, US · Founded 2025 · 4 employees · 12 known investors

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Hillclimb develops training data for recursive self-improvement in AI models, focusing on aggregating human research data and automating reinforcement learning environment creation. The company sells the resulting data to frontier AI laboratories.

Also known as Plun, Inc. · Plun · Plun, Hillclimb

AI & Machine LearningData & InfrastructureDeveloper ToolsEnterprise SoftwareReinforcement LearningUnited States of AmericaAmerica / Canada

Founders & leadership· Y Combinator alumni (F25)

hillclimb was founded in 2025 by Jun Park.

JPJun Park
Jun ParkFounder · CEOJun Park previously worked at DeepMind and studied at Georgia Tech; he also has a background in professional Valorant.
PR
Pruthvi RajaghattaCTO
AB
Alex BerezovskySoftware Engineer
PD
Pranav DevarintiResearch Engineer
IU
Ibrakhim Ustelbay

Investors · 12

Y Combinatorlisted by Y CombinatorSan Francisco · $500K

How we know: the Y Combinator directory · open dataset · 5k.vc investor directory · Not right? Tell us

Abstract VenturesreportedSan Francisco · $250K – $750K

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Andreessen HorowitzreportedMenlo Park · $500K – $50M

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Don Horeported

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FAST — by GETTYLABreportedSan Francisco · $100K

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Felicis VenturesreportedSan Francisco · $500K – $15M

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General CatalystreportedSan Francisco · $30M

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Genius Venturesreported

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Metsu Capitalreported

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Phosphor Capitalreported

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Sequoia CapitalreportedMenlo Park · $100K – $50M

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Images

hillclimb photo

Related companies · 9

DecagonDecagon provides AI agents that enable businesses to deliver personalized customer experiences at scale. The platform targets brands seeking to implement concierge-level service for their customer base.
PathmindPathmind applies deep reinforcement learning to simulations and digital twins to help industrial engineers and simulation modelers improve performance in industrial operations, supply chains, and mining. It generates and deploys decision-making policies into operations.
EdurekaEdureka provides live online courses for continuing professional education, targeting students and corporate learners seeking skill development in technology and related domains. The platform emphasizes high course completion rates through instructor support and ongoing learner engagement.
rct AIrct AI builds AI-driven non-player characters and AI-generated content for the video game industry, offering tools for both game developers and players. It applies deep learning and reinforcement learning to create dynamic, interactive gaming experiences and metaverse content.
UnifyUnify provides AI agents that handle routine business tasks across communications, sales, operations, and engineering by executing pre-built workflows or custom automation. The service serves tech-focused companies and teams looking to offload administrative and repetitive work.
EmeritusEmeritus provides online education and lifelong learning programs, working with universities to offer courses and degree programs to consumers and professionals. It operates across regions including India, APAC, and the Middle East.
VelosVelos replaces outsourced manual work and business process operations with AI-powered automation, handling tasks like data entry, reconciliation, document review, and exception handling for enterprise clients.
Vibrant LabsVibrant Labs builds tools for teams to develop AI systems that function effectively in real-world applications. The company focuses on providing developer tooling for machine learning and AI implementation.
DataCampDataCamp is a learning platform for teams that teaches data and AI skills through hands-on coursework accessible via web browser and mobile app. It serves enterprise customers and development teams seeking to build technical capabilities.

Companies working in the same space as hillclimb.

Legal entities · 1

corporate structure
Plun, Inc.

In the news

hillclimb - Training data derived from human superintelligenceycombinator.com · Nov 2025

Frequently asked questions

What does hillclimb do?
Hillclimb develops training data for recursive self-improvement in AI models, focusing on aggregating human research data and automating reinforcement learning environment creation. The company sells the resulting data to frontier AI laboratories.
Who founded hillclimb?
hillclimb was founded by Jun Park in 2025.
Who are hillclimb's investors?
hillclimb's investors include Ritual Capital, Y Combinator, Abstract Ventures, Andreessen Horowitz, Don Ho, FAST — by GETTYLAB, Felicis Ventures, General Catalyst and 4 more.
Where is hillclimb headquartered?
hillclimb is headquartered in San Francisco, US.