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YC hasn't listed these 19 companies yet

September 22, 2026·data·← all articles

tl;dr: the official Y Combinator startup directory lists 79 Fall 2026 companies as of september 22 2026. the 19 below are YC F26 companies that aren't on it yet, and none of them were on our last fall list either. they go from 2 followers on X to 1,680, and five of them have no company account at all.

the directory is published, not live

a founder gets into Y Combinator, moves, starts building and hiring. the directory entry comes later, on YC's schedule. in between there is a real company with no public record: no listing, no press, often no launch.

that window is the only time an investor can reach a YC founder before every other investor has the same list. these 19 are in it right now.

every entry carries the date frontrun first flagged it. follower counts are as of september 22.

14 with a company account

1. Kiwi AI: the AI agent IDE for teams

"the AI agent IDE for teams." build and share agent workflows, pull skills ranked by real outcomes, run them on any model, and see everything your agents do so you can approve what matters before it leaves the building.

  • flagged: september 18
  • followers on X: 2
  • sector: DevTools
  • founder: @melchen (prev forward deployed engineer at chalk, swe at plaid, cs at MIT)
  • website: withkiwi.ai · X: @with_kiwi_ai
Kiwi AI - the AI agent IDE for teams

2. Praxis: AI that runs a law firm's client journey

"AI that runs a law firm's entire client journey." it books the consultation, runs the conflict check, collects the documents and gets the engagement letter signed, while the lawyer supervises and approves.

Praxis - AI that runs a law firm's entire client journey

3. Bryel Labs: models teams own

"bryel helps teams train models that they own." multimodal post-training and continual learning, out of san francisco.

  • flagged: june 3
  • followers on X: 20
  • sector: AI
  • founder: Kevin Miao, @kjhmiao (teaches at UC berkeley)
  • website: bryel.ai · X: @bryel_labs
Bryel Labs - helping teams train models they own

4. Jinko: travel infrastructure for agents

"the travel infrastructure for agents." one MCP to search, compare and book flights against real-time global inventory, built for AI agents instead of people.

Jinko - the travel infrastructure for agents

5. Quivly AI: an AI workforce for post-sales

"an AI workforce for B2B post-sales." agents that run onboarding, renewals and expansion so the customer team scales without scaling headcount.

Quivly AI - an AI workforce for B2B post-sales

6. ix: machines for AI agents

persistent, autoscaled machines for AI agents. you pay only for the CPU, RAM and disk the machine is using at that moment, and every environment can be forked and snapshotted.

ix - persistent, autoscaled machines for AI agents

7. Native: artificial intuition for marketing

"artificial intuition for marketing." it creates, publishes and improves your social content, with every post approvable by default or fully on autopilot.

Native - artificial intuition for marketing

8. Ploid: people search over every human

"frontier people search over every human." a living index of more than two billion people that you query in plain english, or hand to your own agent. structuring the world's information on people and companies.

Ploid - frontier people search over every human

9. Superserve: computers for long-horizon agents

virtual machines for long-horizon agents. "computers built for agents that need to keep working for hours, not seconds."

Superserve - virtual machines for long-horizon agents

10. Grep: agents for knowledge work you can't get wrong

custom agents for the repetitive knowledge work you can't afford to get wrong. each step is routed to the best model for it, and you run them over API, MCP, on a schedule or as a batch.

  • flagged: july 9
  • followers on X: 327
  • sector: AI
  • founders: @_aj (ceo, 2x YC founder, prev compound, brex, coinbase, google) and @miguelriosen (cto, prev head of platform engineering at brex)
  • website: grep.ai · X: @grepdotai
Grep - custom agents for repetitive knowledge work

11. Clean: an AI GTM system

"get your customers before others do." an AI GTM system that indexes company knowledge, maps warm relationship paths, profiles buyers against ICP signals and runs low-volume outreach.

Clean - get your customers before others do

12. microsandbox: a kernel per untrusted program

"one command gives untrusted code its own kernel on your laptop. no daemon, no root, no account." the sandbox you build locally runs unchanged in their cloud, and credentials are destination-bound, so an agent can use a key without ever holding it.

microsandbox - one command gives untrusted code its own kernel

13. Polygres: retrieval over the postgres you already run

"AI retrieval that feels like extended context." graph, vector and full-text in one query over the postgres you already run, neon, planetscale or supabase included. built by evokoa (@evokoa_ai), a lab making the world's data AI native. 9 tracked accounts already follow it.

Polygres - AI retrieval that feels like extended context

14. Adalat AI: faster courts, as a nonprofit

a legal-tech nonprofit using AI to cut court delays and raise judicial quality in developing countries. the only nonprofit on this list.

Adalat AI - AI to cut court delays in developing countries

no company account yet

15. Ageospatial: mapping all property, infra and land

"mapping all property, infra and land on earth." geospatial AI agents that turn maps, satellite and property data into physical-world intelligence for governments and insurers, anywhere, in seconds.

Ageospatial - mapping all property, infra and land on earth

16. Bayworks: warranty paperwork for car repair

a technician voice-records the cause and correction of a repair, and Bayworks turns it into an OEM-compliant warranty story in seconds.

Bayworks - OEM-compliant warranty stories from a voice note

17. Acyclic Labs: a cockpit for agent swarms

"building tools that help developers ship faster." they make Graphcoder, a cockpit for scaling agent swarms to tasks too big for one agent: fork-join parallelism, isolated workspaces and real-time visibility into every branch.

Acyclic Labs - Graphcoder, a cockpit for agent swarms

18. Tarski Research: environments for research-level reasoning

"training environments for research-level reasoning." RL environments and evals built from research mathematics.

Tarski Research - training environments for research-level reasoning

19. 🥷 stealth: food biomanufacturing

"post-photosynthetic food biomanufacturing @ stealth. YC F26."

  • flagged: september 15
  • sector: Biotech
  • founder: Andre Yeung, @ayyeung42 (bioengineering and cs at stanford). no website yet.

that's 19

all of it came through the frontrun API and MCP server.

if you found this page looking for a YC F26 company list, pair it with the full fall list. the directory will add these 19 over the coming weeks, and the graph will already have the next ones.

the directory will catch up. the social graph was first.

follow from the front, start a free trial →

read next: the full YC fall cohort · YC S26 startups not in the Y Combinator directory · startups flagged before they raised

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