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Epsilab

Active · Long horizon RL environments from real-life data

WebsiteYC profile

Why it ranks

How the rank works
10signal of 100 · rising 10
  • went through YCProgram · this site+4
  • team of 4Team size · YC's directory+3.6
  • hiringHiring · Titles (titles.fru.dev), YC+2

A sum of public facts, not a judgement and not investment advice.

Competitors

AIMangoDeskShared: long horizon, environment, realYC S25San FranciscoStartup →AIPolymathShared: long horizon, environment, simulationYC W26San FranciscoStartup →AIAviroShared: long horizon, reinforcement learning, environmentYC X25San FranciscoStartup →AIWebhoundShared: long horizon, research, agentYC S23San FranciscoStartup →AIBunkerhill HealthShared: long horizon, agentYC W19San FranciscoStartup →OtherPatronus AIShared: environment, simulation, trainingStartup →
Companies closest to Epsilab
Company
MangoDeskShared: long horizon, environment, realYC S25ActiveAI
PolymathShared: long horizon, environment, simulationYC W26ActiveAI
AviroShared: long horizon, reinforcement learning, environmentYC X25ActiveAI
WebhoundShared: long horizon, research, agentYC S23ActiveAI, Data
Bunkerhill HealthShared: long horizon, agentYC W19ActiveAI
Patronus AInot in a program hereShared: environment, simulation, trainingElsewhereOther

Adjacent

AICartpoleShared: frontier model, data labeling, reinforcement learningYC X25San FranciscoStartup →AIBelvedirShared: model training, machine learningYC S26San FranciscoStartup →AITokenlessShared: research lab, reinforcement learning, machine learningYC S26San FranciscoStartup →AISynthShared: long horizon, reinforcement learning, modelYC F24San FranciscoStartup →AISherpa LabsShared: data labeling, reinforcement learning, frontierYC W25San FranciscoStartup →
Companies next to Epsilab
Company
CartpoleShared: frontier model, data labeling, reinforcement learningYC X25ActiveAI, Data
BelvedirShared: model training, machine learningYC S26ActiveAI
TokenlessShared: research lab, reinforcement learning, machine learningYC S26ActiveAI, Devtools
SynthShared: long horizon, reinforcement learning, modelYC F24ActiveAI, Devtools
Sherpa LabsShared: data labeling, reinforcement learning, frontierYC W25ActiveAI, Data

Also from F26 in AI

All of F26
AIMetalcraftAdvancing biological modelsYC F26San FranciscoStartup →AIReificRL environments for superhuman reasoning over timeYC F26San FranciscoStartup →AIAxonnicBringing human dexterity to every robotYC F26San FranciscoStartup →AIEvident MachinesBenchmarks and RL environments for electrical engineeringYC F26San FranciscoStartup →AIHundred100% automated inspection for precision hardware partsYC F26San FranciscoStartup →AILyonFoundation models on enterprise transaction data.YC F26San FranciscoStartup →
Company
MetalcraftAdvancing biological modelsteam of 2ActiveAI, Data
ReificRL environments for superhuman reasoning over timeActiveAI, Devtools
AxonnicBringing human dexterity to every robotteam of 2ActiveAI, Data
Evident MachinesBenchmarks and RL environments for electrical engineeringteam of 2ActiveAI
Hundred100% automated inspection for precision hardware partsteam of 3ActiveAI
LyonFoundation models on enterprise transaction data.team of 2ActiveAI, Data

Founders

  • Evan HuFounder
  • Matthew OlsenFounder
  • Fengjiao PengFounder
  • Joanne WangFounder

About Epsilab

Applied AI research lab focused on RL for frontier model training. Our research and evals cover real-world environment simulation, long-horizon workflows, and multi-player agents, etc.

YC batch
F26 · Fall 2026
Status, per YC
Active
Category
AI, Data
Team size
4
Location
San Francisco, CA, USA
Founded
2026
Checked
6h ago

YC tags: Machine Learning, Reinforcement Learning, B2B, Data Labeling, AI

Changes seen

HiringNov 9, 2026

Started hiring.

Source ↗
Joined a programOct 26, 2026

Joined Y Combinator's Fall 2026 batch (F26).

Source ↗

Epsilab in F26: 219 companies, 89% AI

LinkedIn

Epsilab: questions

Which YC batch was Epsilab in?

Epsilab was in Y Combinator's Fall 2026 batch (F26).

Is Epsilab still active?

Y Combinator lists Epsilab as active.

Who founded Epsilab?

Epsilab's founders, as listed on its YC page: Evan Hu (Founder), Matthew Olsen (Founder), Fengjiao Peng (Founder), Joanne Wang (Founder).

Where is Epsilab based?

Epsilab lists San Francisco, CA, USA as its location on YC's directory.