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Fastest growing X25 companies

The 31 YC X25 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 31 of 31 companies on this list
#CompanyTeam6 mo12 moOpen rolesTotal raisedLast round
1
Industrial data layer for physical RSI
56+331% 0$7.6MSeed$6M, Jun 2026
2
Autonomous Company Infrastructure
15+150%+200%3$28.5MSeries A$28.5M, Aug 2026
3
Intelligence Infrastructure on People and Entities
13+117%+160%YC$500KYC investment$500K, Apr 2025
4
A personal EA in your iMessage
10+100%+43%1$2MSeed$2M, Jun 2025
5
Build autonomous AI agents for enterprise systems
50+92%+355%4
6
The Agent-Native Computer
13+86%+117%YC
7
Vertical AI agents running B2B outbound on autopilot, with human SDRs
140+77%+724%0$6.2MSeed$6.2M, Sep 2025
8
Autonomous security testing for web apps, APIs, cloud, and AI systems
21+75%+200%YC$17.2MSeries A$13M, Jul 2026
9
Agentic AI platform for Pharma GTM teams
39+63%+144%YC$5MSeed$5M, Nov 2025
10
AI Revenue Platform for Post-Acute Care
13+63%+160%3$4.9MSeed$4.4M, Jan 2026
11
Open-source agents to build predictive ML models from a prompt
11+57%+57%YC$2.1MSeed$2.1M, Aug 2025
12
Streamlining Data Capture to Report Creation for Heavy Industries
11+57%+83%0$500KYC investment$500K, Jun 2025
13
quantum-accelerated AI servers
48+50%+118%8$139MSeries A$105M, Mar 2026
14
24/7 Global Stock Exchange
12+50%+50%YC$10MSeed$9.5M, Mar 2026
15
All-In-One AI Growth Partner. Built for Trades.
13+44%+44%0$7.5MSeed$7M, Nov 2025
16
Specialized AI for Every Job
14+40% 0Undisclosed roundJan 2026
17
AI-Native IP Enforcement
18+38%+100%YC$500KYC investment$500K, Mar 2025
18
Your AI Chief of Staff
11+38%+83%YCSeedJul 2025
19
The agentic operating system for modern system integrators.
48+37%+167%3$20.5MSeries A$20M, Apr 2026
20
Test, monitor, and improve your voice and chat AI agents
16+33%+129%YC$4MSeed$4M, Aug 2025
21
Software to monitor, control, and optimize data centers.
13+30%+63%YC$5.1MSeed$5.1M, Dec 2025
22
AI Driven EPC - Weld Fabrication Contractor
18+29%+157%1SeedJun 2025
23
Secure internal apps. Built by AI in seconds. Powered by your data.
14+27%+56%0$10.5MSeed$10M, Dec 2025
24
Function Health for Europe
44+26%+100%3$28.5MSeries A$20M, May 2026
25
We build software factories for engineering teams
10+25%+11%YCSeedJun 2025
26
The agentic CRM for blue-collar services
11+22%+22%0Pre-seedJun 2025
27
Voice data for AI
18+13%+260%YC$3.5MSeed$3M, Nov 2025
28
AI native financial institution
10+11%+11%0SeedApr 2025
29
Industrial Robots that Learn and Operate Like Humans
13+8%+8%YC$500KYC investment$500K, Jun 2025
30
The AI Operator for Financial Services
13+8%−7%2$9.4MNon-equity support$1M, Oct 2025
31
Vertical AI for highly-regulated manufacturing
14+8%+56%1$500KYC investment$500K, Sep 2025

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 X25 companies

How many YC X25 companies are there?

144 companies were in Y Combinator's Spring 2025 batch (X25); 136 are active.

Which YC X25 companies are hiring?

11 companies posted roles in the last 60 days, led by Sygaldry Technologies (8 roles), Sim (4 roles) and Lucis (3 roles). 57 mark themselves as hiring on YC's directory.

Which YC X25 companies are growing fastest?

By team growth over 6 months (10+ people): Linewise (+331%), Naïve (+150%) and Sixtyfour (+117%).

Which YC X25 companies raised the most?

Largest latest rounds in the last 12 months, after their YC batch: Sygaldry Technologies ($105M), Naïve ($28.5M) and Foundation Industries ($25M).

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