The 30 YC S21 companies whose latest reported round, after their YC batch and in the last 12 months, was the largest.
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 | Web search rebuilt for LLMs | 243 | +46% | +117% | 28 | $357M | Series C$250M, May 2026 |
| 2 | Banking, corporate cards, stablecoin payments, available globally. | 98 | +31% | +63% | 3 | $160M | Series C$100M, Apr 2026 |
| 3 | Moving Things Around in Space, Imaging Space Objects When We're Not | 211 | 2 | $128M | Series B$75M, Apr 2026 | ||
| 4 | AI-enabled financial automation and intelligence for CPG Brands | 121 | +89% | +163% | 22 | $75M | Series B$55M, Sep 2026 |
| 5 | Online Training for Healthcare Jobs | 449 | +12% | +33% | 36 | $111M | Series C$55M, Jun 2026 |
| 6 | Fair, simple and accessible financial services | 480 | +4% | +15% | 2 | $86.8M | Corporate round$53M, May 2026 |
| 7 | Payments powering people | 68 | −1% | +8% | 5 | $62M | Series B$40M, Jun 2026 |
| 8 | Building the human layer of AI | 104 | +4% | +33% | 8 | $64.2M | Series B$40M, Nov 2025 |
| 9 | We're building fully automated labs for protein engineering | 40 | +29% | +43% | YC | $50.9M | Series A$40M, Aug 2026 |
| 10 | We visually monitor space objects for governments and defense | 125 | +12% | +21% | 0 | $38.4M | Series B$26.4M, Sep 2026 |
| 11 | Payroll-backed loans and cash advances in Latam | 48 | −2% | +2% | 0 | $28.6M | Series A$24M, Dec 2025 |
| 12 | We make cancer care at home possible. | 67 | +8% | +24% | 0 | $60.6M | Series A$21M, Jan 2026 |
| 13 | Speech and accent coaching app for non-native English speakers | 27 | +29% | +69% | 2 | $27.1M | Series A$21M, Dec 2025 |
| 14 | Unlocking the next generation of mRNA medicines | 35 | +21% | +35% | 0 | $70.9M | Series A$20M, Oct 2026 |
| 15 | The AI-Native Turnkey Alternative Investment Platform (TAIP) | 29 | +93% | +142% | YC | $18.9M | Series A$15M, Sep 2026 |
| 16 | Automated e2e screenshot testing without writing or maintaining tests | 28 | +8% | +87% | YC | $19.1M | Series A$15M, Jul 2026 |
| 17 | Loan management software for private lenders | 30 | +3% | +76% | 1 | $13.6M | Series A$13.5M, Feb 2026 |
| 18 | Discovering drugs that target the DNA regulome | 24 | −8% | −8% | 0 | $27.8M | Seed$11.2M, Sep 2026 |
| 19 | Developer friendly drop in payouts infrastructure | 18 | +20% | +50% | YC | $14.8M | Series A$8.9M, Feb 2026 |
| 20 | The Best Data Infrastructure for Biotechs | 1 | YC | $9.7M | Series A$8M, Jun 2026 | ||
| 21 | We make software for bookkeepers. | 81 | −2% | −9% | 1 | $15.1M | Series A$6.5M, Dec 2025 |
| 22 | Autonomous medical care | 40 | +18% | +60% | 15 | $7.6M | Seed$5.6M, Jan 2026 |
| 23 | Advanced Contract MFG for fast moving hardware companies | 7 | 0 | $4.5M | Pre-seed$4.5M, Dec 2025 | ||
| 24 | Plaid for Brazil: we allow developers to access users' financial data | 48 | +33% | +71% | 0 | $5.2M | Series A$3.5M, Aug 2026 |
| 25 | Truss is a banking and payments network for blue-collar trades. | 14 | +8% | −12% | 1 | $8M | Undisclosed round$3M, Apr 2026 |
| 26 | Nuclear-inspired cooling that turns wasted power into more AI compute | 16 | −6% | 0 | $3.5M | Undisclosed round$1.3M, Feb 2026 | |
| 27 | One-hour antibiotic sensitivity testing | 14 | +8% | +17% | 0 | $3.6M | Seed$750K, Aug 2026 |
| 28 | Uber for Healthcare in Latinamerica | 71 | −1% | −7% | 0 | $43.1M | Series B$750K, Jan 2026 |
| 29 | Vertical takeoff and landing aircraft for major airlines | 51 | −4% | +11% | 3 | $42.1M | Undisclosed round$173K, Apr 2026 |
| 30 | Pioneering Breast Cancer Diagnostics for a Healthier Tomorrow | 19 | +6% | +6% | 0 | $261K | Seed$136K, Jun 2026 |
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
390 companies were in Y Combinator's Summer 2021 batch (S21); 284 are active.
50 companies posted roles in the last 60 days, led by Stepful (36 roles), Exa (28 roles) and ARQ (24 roles). 85 mark themselves as hiring on YC's directory.
By team growth over 6 months (10+ people): Hirebolt (+100%), Aqua (+93%) and Confido (+89%).
Largest latest rounds in the last 12 months, after their YC batch: Exa ($250M), Slash ($100M) and Turion Space ($75M).