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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

Abstract VenturesreportedSan Francisco · $250K – $750K

How we know: Y Combinator's founder network · Not right? Tell us

Andreessen HorowitzreportedMenlo Park · $500K – $50M

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Don Horeported

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FAST — by GETTYLABreportedSan Francisco · $100K

How we know: Y Combinator's founder network · Not right? Tell us

Felicis VenturesreportedSan Francisco · $500K – $15M

How we know: Y Combinator's founder network · Not right? Tell us

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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Ritual CapitalreportedMenlo Park · $100K – $500K

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Sequoia CapitalreportedMenlo Park · $100K – $50M

How we know: Y Combinator's founder network · Not right? Tell us

Images

hillclimb photo

Related companies · 9

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PathmindPathmind applies deep reinforcement learning to industrial simulations and digital twins, helping engineers optimize operations and supply chains with performance gains, and then implements these optimized policies in live systems.
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 develops artificial intelligence systems for non-player characters in video games and metaverse environments, using deep learning and reinforcement learning to create interactive and adaptive gameplay experiences.
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 Y Combinator, Abstract Ventures, Andreessen Horowitz, Don Ho, FAST — by GETTYLAB, Felicis Ventures, General Catalyst, Genius Ventures and 4 more.
Where is hillclimb headquartered?
hillclimb is headquartered in San Francisco, US.