Top accelerator startups

Startups14,448Programs29

14,448 startups · 29 programs

Polymorph

Active · Building secure polymorphic apps

WebsiteYC profile

Why it ranks

How the rank works
8signal of 100 · rising 8
  • went through YCProgram · this site+4
  • team of 4Team size · YC's directory+3.6

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

Competitors

AITrainLoopShared: fine tuningYC W25San FranciscoStartup →AITagflow AIShared: fine tuningAntler 2024IndonesiaStartup →AIUnsloth AIShared: fine tuningYC S24San FranciscoStartup →AIInactiveAirtrain AIShared: fine tuning, scaleYC S22San FranciscoStartup →AISUNShared: founding engineerspeedrun SR006Palo AltoStartup →OtherTogether AIShared: fine tuningStartup →
Companies closest to Polymorph
Company
TrainLoopShared: fine tuningYC W25ActiveAI, Devtools
Tagflow AIShared: fine tuningAntler 2024Not statedAI
Unsloth AIShared: fine tuningYC S24ActiveAI, Devtools
Airtrain AIShared: fine tuning, scaleYC S22InactiveAI, Devtools
SUNShared: founding engineerspeedrun SR006Not statedAI
Together AInot in a program hereShared: fine tuningElsewhereOther

Adjacent

AIweweb.ioShared: building secure, engineeringYC W21ParisStartup →AICumulus LabsShared: fine tuning, inference, buildingYC W26San FranciscoStartup →AIDatacurveShared: fine tuning, scaleYC W24San FranciscoStartup →AIAcquiredOpenPipeShared: fine tuning, backgroundYC S23SeattleStartup →AILaminiShared: fine tuning, engineering, scalePlug and PlayUnited StatesStartup →
Companies next to Polymorph
Company
weweb.ioShared: building secure, engineeringYC W21ActiveAI, Devtools
Cumulus LabsShared: fine tuning, inference, buildingYC W26ActiveAI, Devtools
DatacurveShared: fine tuning, scaleYC W24ActiveAI
OpenPipeShared: fine tuning, backgroundYC S23AcquiredAI, Devtools
LaminiShared: fine tuning, engineering, scalePlug and Play Not statedAI, Devtools

Also from W26 in AI

All of W26
AI/dev/fast/dev/fast is the AI-native code forgeYC W26San FranciscoStartup →AI10x ScienceThe AI-native platform for next-generation protein characterization.YC W26San FranciscoStartup →AI21stUI building blocks for the agentic internetYC W26San FranciscoStartup →AIAemonThe Forward-Deployed AI Research EngineerYC W26San FranciscoStartup →AIAgentic FabriqThe control plane for AI agents.YC W26San FranciscoStartup →AIAlt-XBuilding the best venue for private markets exposure.YC W26Los AngelesStartup →
Company
/dev/fast/dev/fast is the AI-native code forgeteam of 4ActiveAI, Devtools
10x ScienceThe AI-native platform for next-generation protein characterization.team of 5hiringActiveAI
21stUI building blocks for the agentic internetteam of 3ActiveAI, Devtools
AemonThe Forward-Deployed AI Research Engineerteam of 3hiringActiveAI, Devtools
Agentic FabriqThe control plane for AI agents.team of 2ActiveAI
Alt-XBuilding the best venue for private markets exposure.team of 2ActiveAI, Data

Founders

  • Andrew SyFounder/CEO

About Polymorph

Team has extensive startup, AI, and math backgrounds: - founding engineer at a unicorn - ML infrastructure @ Scale AI (inference), AWS Bedrock (fine-tuning) - ads engineering @ Meta & Twitch - IMO & IOI medalists

YC batch
W26 · Winter 2026
Status, per YC
Active
Category
AI
Team size
4
Location
San Francisco, CA, USA
Founded
2026
Checked
6h ago

Polymorph in W26: 199 companies, 81% AI

LinkedIn

Polymorph: questions

Which YC batch was Polymorph in?

Polymorph was in Y Combinator's Winter 2026 batch (W26).

Is Polymorph still active?

Y Combinator lists Polymorph as active.

Who founded Polymorph?

Polymorph's founders, as listed on its YC page: Andrew Sy (Founder/CEO).

Where is Polymorph based?

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