182 YC companies say they ship an MCP server. 14 answered.

Installmap crawled every reachable Y Combinator company on September 23 and published the result as a CSV, under CC BY 4.0. Their headline: 43 of the 119 sampled YC companies with an MCP server show no public API at all. Startups are skipping the API and going straight to MCP.

That dataset is now a source in nichedb.dev/c/mcp. It had one gap worth filling. The CSV knows that a company has a server, but mostly not where it is. The evidence column says "home text MCP Server" about as often as it says "mcp subdomain 200".

So we went and knocked.

What knocking found

Each company became an OpenMCP record (logicsrc.com/openmcp). The address comes from Installmap's evidence first, then from the official MCP registry's remotes under the company's reverse domain name (io.anakin, com.bitmovin), then from the company's own /.well-known/openmcp.json. After that, an unauthenticated initialize and tools/list, the same handshake any MCP client does.

	Companies
In the dataset	182
An endpoint we could find	53
Answered and listed their tools	14
Answered 401 or 403 (a real server that wants a key)	39
Serve an OpenMCP descriptor	0
Only mention MCP on the site	114

The biggest open ones: NewsCatcher with 61 tools, Clueso with 44, Pluggy with 31.

A 401 counts. That is a server that exists and wants a credential this probe will never send, so it is listed as offline with the reason attached, not dropped. A 405 to a POST, or an HTML page sitting at /mcp, does not count. Several companies have a nice page at /mcp that is marketing, not a relay.

Who is behind them

Every row also carries the company's own accounts and its founders. The homepage is the real source here. 165 of the 182 link at least one account, and schema.org markup named founders on 28 sites. Wikidata matched only 25 of these companies on their official website, and knew the founders of 2.

If a homepage links four X accounts because it quotes three customers, we keep the one whose handle matches the company, and if none does we keep nothing. A wrong handle is worse than a missing one.

The companies and the 49 founders are also OpenProfile documents in nichedb.dev/c/profiles, so a founder is someone you can follow, not a string in a JSON blob.

We did not read ycombinator.com. Its company pages carry founders and socials in the markup, but its terms forbid scraping, and the popular yc-oss dataset is a scrape of it.

The zero

Not one of these companies serves an OpenMCP descriptor. That is the one file that would have made most of this unnecessary: where the endpoint is, what auth it wants, which tools work without a key. The whole thing is five lines of JSON at /.well-known/openmcp.json.

Browse them at https://nichedb.dev/c/mcp?tag=yc. Data: Installmap, September 2026 (CC BY 4.0).