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Fastest growing X26 companies

The 18 YC X26 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.

Showing 18 of 18 companies on this list
#CompanyTeam6 mo12 moOpen rolesTotal raisedLast round
1
Scale marketing campaigns across hundreds of personas
20+233%+300%0$500KYC investment$500K, Jun 2026
2
Real-world training data for frontier AI labs and robotics.
53+194%+152%YC
3
Agents that own the work
13+160% YC$45.8MUndisclosed round$12.8M, Oct 2026
4
Patreon for AI Originals
22+144% 0$500KYC investment$500K, Jun 2026
5
Counter Drone Systems. $1.6m sales. We delivered for the DoW.
22+120%+214%10$500KYC investment$500K, Jun 2026
6
We make the most compact nuclear reactors
13+117% 0$32.1MUndisclosed round$620K, Sep 2026
7
Ploy turns your website into your company's growth engine.
27+93% 2$27MSeed$27M, Jun 2026
8
AI Scheduling for Short Haul Trucks
21+91%+91%0$500KYC investment$500K, Jun 2026
9
robots & software for farms
16+78% 0$500KYC investment$500K, May 2026
10
AI primary care doctor
10+67% YC$12MPre-seed$12M, May 2026
11
Plena is the AI operating system for specialty medical practices
10+67%+67%YC$500KYC investment$500K, Jun 2026
12
Agentic hiring marketplace
16+60% YC$500KYC investment$500K, May 2026
13
AI-native observability and security platform
12+50% 0$8.5MSeed$8M, Jun 2026
14
Tolmo is the AI security platform that secures every layer of cloud…
13+44% 5$22MSeed$22M, Jun 2026
15
Vanta for physical products
21+31%+200%1$13.6MSeed$11M, Sep 2026
16
Computer use agents to deploy enterprise marketing campaigns
14+27%+8%YC$11.8MSeed$9.8M, Jun 2026
17
Design your home instantly with AI
13+18% 0$17.6MSeed$16M, May 2026
18
AI recruiters for staffing agencies
29+4%−3%YC$1MYC investment$500K, Mar 2026

How this works

1. The roster

Every launched company in YC's public directory, with its batch, status, industry and location. New companies show up the week YC lists them.

2. The numbers

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.

3. The lists

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.

Built with Crustdata. Get your own API key and build your own.

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.

  • Company search for team size, growth and funding
  • Job search with a count by company, for who is hiring and for what
  • A watch that re-runs the search weekly and sends only what changed
# 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

Questions about YC X26 companies

How many YC X26 companies are there?

192 companies were in Y Combinator's Spring 2026 batch (X26); 188 are active.

Which YC X26 companies are hiring?

13 companies posted roles in the last 60 days, led by 9 Mothers (10 roles), Tolmo (5 roles) and Madrone (5 roles). 65 mark themselves as hiring on YC's directory.

Which YC X26 companies are growing fastest?

By team growth over 6 months (10+ people): InstaAgent (+233%), Hub (+194%) and Tasklet (+160%).

Which YC X26 companies raised the most?

Largest latest rounds in the last 12 months, after their YC batch: Ploy ($27M), Tolmo ($22M) and Drafted ($16M).

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