13% of YC startups know you're visiting even if you never enter. 5.7% look up your name

By Installmap Research. Published 2026-09-15. Updated 2026-09-27. Version v1.1.

We fetched the homepage of every company in the Y Combinator directory with a headless browser and recorded which scripts loaded. On 307 of the 5,386 homepages a person-level identification script loaded with the page: RB2B, Warmly, Vector, Retention.com, Customers.ai, Opensend or Hyros. These vendors match a visitor's browser to a name and an email address through a data broker's identity graph and hand it to the site's sales team. On 259 of the 307 there was no consent-management tool on the page. All 307 companies are listed below by name. Another 517 homepages ran a company-level script that resolves the visitor's IP address to an employer and stops there. HubSpot's and LinkedIn's own company lookups are not counted here; see Method.

Visitor identification statistics 2026

1. 707 of 5,386 Y Combinator homepages (13.1%), about one in eight, run a dedicated visitor-identification vendor.

Source: Installmap, We opened 5,386 YC startup homepages. 307 tried to put a name on us, September 2026. Data: homepage crawl, September 2026.

1. 307 of those YC homepages (5.7%), about one in eighteen, run a person-level vendor that tries to put a name and email on the visitor.
2. 259 of the 307 YC person-level taggers (84.4%) have no consent-management tool on the same homepage.
3. 32 of 472 Fortune 500 homepages (6.8%) run a visitor-identification vendor. All 32 are company level. None of the Fortune 500 homepages runs a person-level one.
4. 20.7% of unicorn homepages and 16.5% of Inc 5000 homepages run at least one vendor.
5. The YC share rises with team size: 9.4% at 1-10 people, 18.4% at 11-50, 21.7% at 51-200 and 26.6% at 201-1,000. The Fortune 500, a separate list, sits at 6.8%.
6. The leading vendor changes by list. Apollo.io Tracker leads YC at 3.2%, ZoomInfo WebSights leads the Inc 5000 at 6.6% and ties Qualified on the unicorns at 7.1%, and Demandbase leads the Fortune 500 at 2.3%.

We expected the Fortune 500 to be the heavy users. Account-based marketing tools are sold to large companies with large sales teams. The Fortune 500 came last of the four lists instead, and the highest-ranked company with a tag on its homepage is Dell Technologies at rank 41. No company above it on the list had one on the homepage we scored.

The 307 YC startups whose homepage tries to name the visitor

Every YC company on whose homepage one of the seven person-level vendors loaded, in alphabetical order. "Consent tool" says whether one of the 11 consent-management products we fingerprint was on the same page. Source: domains.csv in the dataset.

13.1% of YC homepages run a visitor-identification vendor and 6.8% of the Fortune 500 do

The unicorn list has the highest any-vendor share at 20.7%, with 207 of 1,000 homepages. The Inc 5000 follows at 16.5% (804 of 4,886), YC at 13.1% (707 of 5,386) and the Fortune 500 at 6.8% (32 of 472).

The person-level order is different. YC has the highest person-level share at 5.7%, then the Inc 5000 at 4.5% (220 homepages), the unicorns at 3.4% (34) and the Fortune 500 at 0.0%. Company-level shares are 9.6% on YC (517 homepages), 13.8% on the Inc 5000 (672), 20.2% on the unicorns (202) and 6.8% on the Fortune 500 (32).

A homepage can run both kinds, so the person-level and company-level counts add up to more than the any-vendor count. Many sites that install one vendor install another: 43.0% of unicorn taggers run two or more (89), against 30.8% on YC (218), 26.0% on the Inc 5000 (209) and 18.8% on the Fortune 500 (6).

The YC share climbs from 9.4% at 1-10 people to 26.6% at 201-1,000

Among YC companies with 1-10 people, 302 of 3,214 (9.4%) run a vendor. The share about doubles to 18.4% at 11-50 people (243 of 1,318), reaches 21.7% at 51-200 (105 of 483) and 26.6% at 201-1,000 (41 of 154). The 29 YC companies listing more than 1,000 people are too few for a share. The Fortune 500 row, at 6.8%, is below even the 1-10 rung at 9.4%.

The person-level share peaks earlier. It is 4.4% at 1-10 people, 8.4% at 11-50, 8.1% at 51-200 and 5.8% at 201-1,000.

Apollo.io Tracker leads YC at 3.2%, ZoomInfo WebSights the Inc 5000 at 6.6%

Shares below are of all scored homepages in the group. The top ten rows per list are shown; the full list is in by_group.csv.

Y Combinator (n=5,386)

Apollo.io Tracker is on 172 YC homepages (3.2%). The next two are both person level: RB2B on 154 (2.9%) and Vector on 124 (2.3%). ZoomInfo WebSights is fourth at 1.4%. The top three vendors appear on 387 of the 707 YC tagger domains (54.7%).

Inc 5000 (n=4,886)

ZoomInfo WebSights is on 322 Inc 5000 homepages (6.6%), more than twice Apollo.io Tracker at 2.8%. RB2B is third at 2.4%. The top three appear on 530 of the 804 tagger domains (65.9%).

Unicorns (n=1,000)

ZoomInfo WebSights and Qualified tie on the unicorn list with 71 homepages each (7.1%). Qualified is one of the four vendors we added in v1.1. 6sense is third at 5.1%. The top three appear on 145 of 207 tagger domains (70.0%).

Fortune 500 (n=472)

Demandbase is on 11 Fortune 500 homepages (2.3%) and ZoomInfo WebSights on 10 (2.1%). Dealfront Leadfeeder and 6sense tie for third with 5 each. Nine vendors appear on the list at all, every one of them company level.

All 32 Fortune 500 taggers stop at the company level

All 32 Fortune 500 companies with a tag run company-level vendors only. Dell Technologies at rank 41 is the highest on the list, followed by Lockheed Martin at 61 and International Business Machines at 66. Salesforce, at rank 114, runs Demandbase on salesforce.com. Six of the 32 run two vendors at once: Fiserv, Cognizant Technology Solutions, Automatic Data Processing, Lumen Technologies, Palo Alto Networks and Packaging Corp. of America.

84.4% of YC person-level taggers have no consent-management tool on the page

259 of the 307 YC homepages running a person-level vendor (84.4%) have none of the 11 consent-management tools we fingerprint on the same page. On the Inc 5000 it is 173 of 220 (78.6%). The unicorns are much lower at 38.2%, 13 of 34. The Fortune 500 has no person-level taggers, so there is no share to give.

We count consent tools here. A company can build its own cookie banner, and a hand-built banner leaves no vendor fingerprint for us to find, so some of these homepages may still show one. So the share counts sites that run a person-level identifier with no known consent product beside it.

YC batches from 2023 have the highest share at 21.5%

Years with fewer than 100 scored homepages (2005 to 2011, 2013 and the single 2027 company) are left out; the counts are in yc_by_year.csv.

The 2023 batches have the highest share, 95 of 441 homepages (21.5%), and the highest person-level share at 11.3%. The 2024 batches follow at 18.4% and 10.0%. From 2012 to 2022 the any-vendor share stays between 9.2% and 16.5%.

The 2025 rows (10.2%) and 2026 rows (5.6%) are not comparable with the rest. We crawled those companies soon after their batch, and a young company has often not installed a sales tool on its site yet. Their low shares come from when we looked, so they do not show a decline.

36.6% of Inc 5000 software companies run a vendor and 2.2% of legal firms do

The table shows the 17 Inc 5000 industries with at least 100 scored homepages. The top five by any-vendor share are software at 36.6%, artificial intelligence and data at 36.0%, IT services at 27.2%, human resources at 27.1% and logistics and transportation at 24.4%. The bottom five are consumer products at 6.1%, government services at 4.4%, construction at 4.2%, consumer services at 4.0% and legal at 2.2%.

Advertising, marketing and PR ranks sixth on any vendor at 22.6% but third on person level at 9.3%, behind artificial intelligence and data at 11.2% and software at 10.0%. Consumer products has a low any-vendor share of 6.1% but a person-level share of 5.3%, so most of its taggers use a person-level tool.

What changed in v1.1

We added four company-level vendors to the fingerprint list: Qualified, Default, Common Room and Reo.dev. We then re-scored the whole homepage archive and removed duplicated rendered rows that had counted some domains twice. The YC any-vendor share moved from 12.1% in v1.0 to 13.1%. The v1.0 title was "No Fortune 500 homepage identifies visitors by name. 5.7% of YC homepages do". The Fortune 500 still has no person-level tagger.

Method

A homepage counts as a hit when it loads a fingerprinted script from one of the 30 dedicated visitor-identification vendors listed above. Each rule matches the hostnames that the vendor's own snippet loads. A vendor's name in a consent banner's provider list, a Content-Security-Policy header or an opt-out link does not count.

Person level means the vendor tries to match the visitor to an individual, with a name and an email address. Company level means the vendor resolves the visitor's IP address to a company and stops there.

These scripts are injected by JavaScript, so we score the rendered fetch of each homepage. Where a domain has a rendered record, it wins. Where it has only a plain record, we count that.

Both the Fortune 500 and the Inc 5000 are the 2026 lists. We print no share on a base under 100 homepages, and counts from one to four print as "<5".

We did not count HubSpot's built-in reverse-IP lookup or the LinkedIn Insight Tag. Both can tell a site which companies visit it, and counting them would raise the YC share to 24.9%, about one in four (HubSpot alone 19.8%, LinkedIn Insight alone 20.9%). This post counts dedicated visitor-identification vendors only.

Limitations

• We see the homepage only. A tag that loads only on a pricing page, a demo form or behind a login is missed, so every share here is a floor.
• The data comes from a single crawl.
• A fingerprint means the script is on the page. It does not mean the script identified any given visitor.
• "No consent tool detected" does not mean "no banner". A hand-built banner leaves no fingerprint.
• YC team size is self-reported to YC in the company directory. 130 YC companies list a team size of 0; we treat that as unknown, so they are in no rung.
• The Fortune 500 row in the team-size table is a different kind of group from the YC rungs. It is a separate list of companies, shown for comparison, and not the next size band.

Who paid

This report is self-funded. Nobody paid to be included or left out. Installmap sells technographic data exports.

Cite this report

Installmap Research, "13% of YC startups know you're visiting even if you never enter. 5.7% look up your name", installmap.com, 2026-09-27, https://installmap.com/research/visitor-identification-tags

Downloads

Files:

• groups.csv
• by_group.csv
• yc_by_team_size.csv
• yc_by_year.csv
• inc_by_industry.csv
• fortune500_taggers.csv
• domains.csv
• README.md
• METHOD.md

Data licensed CC BY 4.0. Source: Installmap, September 2026.