API Evangelist Paper · Portfolio Report
The Y Combinator API Portfolio
Every Y Combinator company that ships an API, scored the way a machine reads it — and why the batch is agent-native and governance-empty at the same time.
About this paper
I read Y Combinator’s portfolio the way a machine reads it — not the launch tweet, the evidence. YC’s public company list resolves to more than eight hundred companies in my catalog, and 190 of them ship a public API I could pull, parse, and score on the same rubric I apply to Stripe. This report is about those 190, because the interface is the part of a seed-stage company you can inspect before the deck catches up to reality.
Here is the headline, two facts that should not sit together but do. Y Combinator has the most agent-native API book of any fund I can measure — 95 of 190 providers (50%) are agent-native, a higher share than a16z, and its companies ship MCP and agent skills at rates above the mature funds — and it also has almost no exemplars: just four companies clear the 70-point band, the fewest of any deeply-harvested fund. YC’s companies are, disproportionately, born speaking the agentic protocols, and at the very same time 95 of the 136 upper-band providers score a flat zero on governance. This is a portfolio of seedlings that learned to talk to agents before they learned to run an operation. If the a16z book — the first report in this series — is a fund’s mature estate, YC is the nursery those exemplars are drawn from. This report reads that book company by company: the AI-monoculture decomposition, the Kin Score facet-by-facet, the agent-readiness table, the honest split between the genuinely born-agentic companies and the ones wearing the label, the head-to-head against seven rival funds, and the Series-A funnel hiding in the developing band.
What's inside
- Executive summary — the agent-native accelerator, and the tell in its own book
- The accelerator, and the book — the 190 API-bearing companies
- Portfolio decomposition — an AI monoculture (43% AI, almost no crypto)
- The composite Kin Score of the book — governance is 20/100
- Agent-readiness of the portfolio — where YC actually wins, and the born-agentic seedlings
- The peer-fund benchmark — the nursery and the estate (YC vs. a16z and five more)
- The crown jewels — the four exemplars and the climbers
- Standards and the agentic turn — a batch born into it
- Security, auth, scopes, and compliance posture across the book
- The AI question, and the whitespace — the Series-A funnel
- The investable thesis — for founders, seed/Series-A, and growth funds
database Includes the AI data bundle
This report ships with a machine-readable data bundle — the evidence behind every number, packaged to drop straight into the AI tool of your choice. Converse with the research you bought, check any claim against the source data, and take it further than the PDF.
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