Top accelerator startups

Startups14,448Programs29

14,448 startups · 29 programs

Cumulus Labs

Active · The Fastest Multimodal Inference OS

WebsiteYC profile

Why it ranks

How the rank works
9signal of 100 · rising 9
  • went through YCProgram · this site+4
  • team of 2Team size · YC's directory+2.5
  • hiringHiring · Titles (titles.fru.dev), YC+2

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

Competitors

AIInactiveAirtrain AIShared: fine tuning, evaluation, productionYC S22San FranciscoStartup →AITrainLoopShared: fine tuningYC W25San FranciscoStartup →AITagflow AIShared: fine tuningAntler 2024IndonesiaStartup →AIUnsloth AIShared: fine tuningYC S24San FranciscoStartup →AICTGTShared: fine tuning, fail, engineeringYC F24San FranciscoStartup →OtherTogether AIShared: fine tuningStartup →OtherPositronShared: inferenceStartup →
Companies closest to Cumulus Labs
Company
Airtrain AIShared: fine tuning, evaluation, productionYC S22InactiveAI, Devtools
TrainLoopShared: fine tuningYC W25ActiveAI, Devtools
Tagflow AIShared: fine tuningAntler 2024Not statedAI
Unsloth AIShared: fine tuningYC S24ActiveAI, Devtools
CTGTShared: fine tuning, fail, engineeringYC F24ActiveAI, Devtools
Together AInot in a program hereShared: fine tuningElsewhereOther
Positronnot in a program hereShared: inferenceElsewhereOther

Adjacent

AIZibra LabsShared: fine tuning, inference, buildingYC X26San FranciscoStartup →AISazabiShared: observability, engineering, infrastructureYC X26San FranciscoStartup →AIOneTriangleShared: inference, fastest, infrastructureYC S26San FranciscoStartup →AIPolymorphShared: fine tuning, inference, engineeringYC W26San FranciscoStartup →AIBeamShared: inference, infrastructureYC W22New York CityStartup →
Companies next to Cumulus Labs
Company
Zibra LabsShared: fine tuning, inference, buildingYC X26ActiveAI, Devtools
SazabiShared: observability, engineering, infrastructureYC X26ActiveAI, Devtools
OneTriangleShared: inference, fastest, infrastructureYC S26ActiveAI, Devtools
PolymorphShared: fine tuning, inference, engineeringYC W26ActiveAI
BeamShared: inference, infrastructureYC W22ActiveAI, 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

  • Veer ShahFounder/CEO

About Cumulus Labs

Cumulus Labs lets engineering teams ship AI in production without needing a dedicated ML platform team. Right now, companies building AI products are forced to stitch together separate vendors for routing, observability, evaluation, fine-tuning, and inference. This fragmented approach is brittle, expensive, and is a common reason enterprises fail with AI. We replace that entire stack with a single unified platform. Developers can keep their existing code while instantly upgrading to a unified platform that handles routing, semantic caching, continuous shadow evaluation, simulated data, and one-click fine-tuning. Behind the platform is Ion, our proprietary inference engine running on a custom NVIDIA Grace GPU fleet. Ion uses in-house custom GPU kernels to deliver 30 to 50 percent more throughput than standard vLLM or SGLang, giving our customers SOTA inference economics.

YC batch
W26 · Winter 2026
Status, per YC
Active
Category
AI, Developer tools
Team size
2
Location
San Francisco, CA, USA
Founded
2025
Checked
10h ago

Cumulus Labs in W26: 199 companies, 81% AI

LinkedIn

Cumulus Labs: questions

Which YC batch was Cumulus Labs in?

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

Is Cumulus Labs still active?

Y Combinator lists Cumulus Labs as active.

Who founded Cumulus Labs?

Cumulus Labs's founders, as listed on its YC page: Veer Shah (Founder/CEO).

Where is Cumulus Labs based?

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