Get an API keyGet an API keyThe 18 YC S15 companies whose team grew the most in the last 6 months (active companies with 10+ people).
Updated weekly, last on November 9, 2026. Roster from Y Combinator's public directory.
| # | Company | Team | 6 mo | 12 mo | Open roles | Total raised | Last round |
|---|---|---|---|---|---|---|---|
| 1 |  An online guide that tells talented graduates how to maximise the… | 121 | +32% | +78% | 0 | $120K | YC investment$120K, Aug 2015 |
| 2 |  The sleep fitness company. | 282 | +17% | +26% | 16 | $302M | Series D$50M, Mar 2026 |
| 3 |  The 401(k) for small and medium-sized businesses. | 930 | +12% | +20% | 36 | $915M | Undisclosed round$100M, Oct 2025 |
| 4 |  The Infrastructure Identity Company | 329 | +12% | +31% | 6 | $169M | Series C$110M, May 2022 |
| 5 |  The fundraising platform for schools. | 148 | +9% | +18% | 9 | $50M | Private equity$50M, Sep 2022 |
| 6 |  Powers OTT online video providers with video developer tools. | 180 | +8% | +10% | 2 | $95.3M | Debt$3M, Oct 2024 |
| 7 |  Move anything, anytime, anywhere | 179 | +8% | +13% | 1 | $3.9M | Seed$3.8M, Jun 2017 |
| 8 |  A flexible work app that connects businesses with hourly workers. | 2,747 | +7% | +16% | 2 | $148M | Series D$60M, May 2023 |
| 9 |  Reliable and affordable solar energy in developing countries. | 17 | +6% | +6% | 0 | $120K | YC investment$120K, Aug 2015 |
| 10 |  The only R&D data cloud for life sciences | 227 | +6% | +32% | 13 | $114M | Undisclosed round$15M, Feb 2026 |
| 11 |  Digital trade finance and B2B commerce company | 444 | +5% | +16% | YC | $578M | Debt$50M, Oct 2025 |
| 12 |  Tesorio is the cash flow performance platform that helps finance… | 44 | +5% | −2% | 0 | $33.9M | Series B$17M, Jul 2022 |
| 13 |  Scentbird is a luxury fragrance subscription service. | 242 | +4% | +10% | 2 | $29.6M | Undisclosed round$820K, Nov 2023 |
| 14 |  Gemnote is the easiest way to design, create and send custom products. | 28 | +4% | +22% | YC | $120K | YC investment$120K, Aug 2015 |
| 15 |  AI-powered contract management | 868 | +3% | +15% | 1 | $334M | Series E$150M, Jan 2022 |
| 16 |  Long range, wireless energy distribution that scales | 39 | +3% | −5% | YC | $39.1M | Grant$30M, Jun 2026 |
| 17 |  High volume hiring made simple | 425 | +2% | +5% | 14 | $219M | Series C$100M, Jun 2022 |
| 18 |  | 369 | 0% | +4% | 0 |
Every launched company in YC's public directory, with its batch, status, industry and location. New companies show up the week YC lists them.
Each company is matched to Crustdata by its website. Crustdata adds team size and its change over 6 and 12 months, open roles from job postings, reported funding, and founders' past employers.
Hiring the most counts distinct roles posted in the last 60 days. Growth needs 10+ people today, shrinking 20+ a year ago, so tiny teams do not top the lists. Rebuilt every week.
The numbers on this page come from three Crustdata API calls. Crustdata tags 5,000+ companies with Y Combinator as an investor; swap the filter for any investor, industry or headcount range and track your own list, with founders' work emails one call away.
# 1. every company with Y Combinator as an investor curl https://api.crustdata.com/company/search \ -H "authorization: Bearer $CRUSTDATA_API_KEY" \ -H "x-api-version: 2025-11-01" \ -d '{ "filters": { "field": "funding.investors", "type": "in", "value": ["Y Combinator"] }, "fields": ["basic_info.name", "headcount.total", "headcount.growth_percent", "funding.total_investment_usd"], "limit": 100 }' # 2. open listings per company, last 60 days (limit 0 = counts only) curl https://api.crustdata.com/job/search \ -H "authorization: Bearer $CRUSTDATA_API_KEY" \ -H "x-api-version: 2025-11-01" \ -d '{ "filters": { "op": "and", "conditions": [ { "field": "company.basic_info.company_id", "type": "in", "value": [...] }, { "field": "metadata.date_added", "type": "=>", "value": "2026-08-24" } ]}, "limit": 0, "aggregations": [{ "type": "group_by", "field": "company.basic_info.company_id", "agg": "count" }] }' # 3. the same company filter as a weekly watch: POST /watch/company/search
104 companies were in Y Combinator's Summer 2015 batch (S15); 44 are active.
16 companies posted roles in the last 60 days, led by Human Interest (36 roles), Eight Sleep (16 roles) and Fountain (14 roles). 18 mark themselves as hiring on YC's directory.
By team growth over 6 months (10+ people): 80,000 Hours (+32%), Eight Sleep (+17%) and Human Interest (+12%).
Largest latest rounds in the last 12 months, after their YC batch: Eight Sleep ($50M), TetraScience ($15M) and Cofactor Genomics ($1.2M).