Y Combinator has 839 portfolio companies tracked on the network, 838 of them matched, at apis.io/vcs/y-combinator/.
Portfolio average: 22.7, an emerging-band composite. Agent readiness across the book: 97 agent-native, 85 agent-ready, landing the portfolio in the agent-aware band.
The band distribution
| Band | Companies |
|---|---|
| Exemplar | 7 |
| Strong | 21 |
| Developing | 115 |
| Thin | 93 |
| Emerging | 186 |
| Minimal | 416 |
416 of 838 — 50% of the book — sits in the minimal band.
The top of the book
| Company | Score | Band | APIs |
|---|---|---|---|
| Stripe | 84.5 | Exemplar | 159 |
| Zapier | 79.3 | Exemplar | 13 |
| Webflow | 74.1 | Exemplar | 23 |
| GitLab | 72.9 | Exemplar | 44 |
| Ironclad | 72.5 | Exemplar | 13 |
| Paystack | 72.4 | Exemplar | 21 |
| Amplitude | 70.4 | Exemplar | 33 |
| ReadMe | 68.4 | Strong | 14 |
| Kita | 67.1 | Strong | 14 |
| Mixpanel | 67.1 | Strong | 22 |
| Plivo | 66.4 | Strong | 24 |
| DoorDash | 65.7 | Strong | 12 |
Stripe at 84.5 is the highest composite in either portfolio covered this week — higher than any Insight Partners company, higher than any provider profiled in these seven days.
YC versus Insight
The comparison with Friday’s Insight Partners piece is the useful part:
| Y Combinator | Insight Partners | |
|---|---|---|
| Companies on network | 838 | 797 |
| Portfolio average | 22.7 | 26.0 |
| Exemplar | 7 | 12 |
| Minimal | 416 (50%) | 304 (38%) |
| Agent-native | 97 | 68 |
Insight’s book scores higher on average and has more exemplars. YC’s book has more agent-native companies — 97 against 68 — despite a lower composite.
That is a stage effect, and it is the most interesting number here. Insight invests at growth stage in established software companies; those companies have mature, well-documented APIs, hence the higher average. YC funds at seed, where half the portfolio has barely shipped a product, hence 50% minimal.
But the YC companies that have shipped built after the agent-native conventions settled. A 2024-vintage seed company shipping an API today starts with OpenAPI, structured errors, and an MCP server as defaults. A 2015-vintage growth company retrofits them.
Takeaway
838 companies, 7 exemplars, half the book at minimal, and Stripe at 84.5 anchoring the top. YC’s portfolio scores lower and reads more agent-native than a growth-stage book — the long tail is young, and the ones that ship are shipping against newer defaults.
Browse the portfolio at apis.io/vcs/y-combinator/.