What 3,791 YC startups build their websites with

We fetched the homepage of every YC company from the 2021 to 2026 batches. Then we tested how much of each one AI crawlers can read, and checked 114 AI company homepages the way an enterprise customer reads them.

Book a call See the Free Website Audit

In short

The study, in short

Updated 17 Oct 2026

On 10 Oct 2026 we fetched the homepages of 3,791 YC companies from the 2021 to 2026 batches. 2,945 answered. Next.js was the most common platform: 1,060 of the 2,945. At companies with 16 to 50 people, Webflow led with 120 of 385. Client-rendered single-page apps, the kind AI builders make, grew from 20 of 522 homepages in the 2021 batch to 70 of 648 in 2026. On 77 of them, AI crawlers could read a median of 8 words. Framer homepages showed a median of 1,543.

The numbers

Counts, not rounded. The method is further down the page.

Checked 17 Oct 2026

2,945 of 3,791

YC homepages from the 2021 to 2026 batches that answered when we fetched them.

Source: Pentaclay YC website study, 10 Oct 2026

120 of 385

Companies with 16 to 50 people whose homepage runs on Webflow, more than any other platform at that size.

Source: Pentaclay YC website study, 10 Oct 2026

310 of 648

Homepages in the 2026 batch that run on Next.js.

Source: Pentaclay YC website study, 10 Oct 2026

70 of 648

2026-batch homepages that are client-rendered single-page apps. In the 2021 batch it was 20 of 522.

Source: Pentaclay YC website study, 10 Oct 2026

8 words

The median AI crawlers could read on 77 client-rendered single-page homepages. Framer homepages: 1,543.

Source: Pentaclay YC website study, 10 Oct 2026

1,001 of 2,945

Homepages served from Vercel.

Source: Pentaclay YC website study, 10 Oct 2026

Platforms by YC batch

Number of homepages on each platform. “Homepages” is how many answered in that batch. Other platforms and sites we couldn’t name make up the rest of each row.

Batch	Homepages	Next.js	Webflow	Framer	Astro	Single-page app	WordPress
2021	522	113	150	26	22	20	50
2022	467	117	120	30	19	22	49
2023	351	120	82	29	19	15	11
2024	445	164	82	55	28	34	5
2025	512	236	27	47	41	49	3
2026	648	310	14	28	54	70	2
All	2,945	1,060	475	215	183	210	120

Source: Pentaclay YC website study. Each homepage fetched once on 10 Oct 2026.

Platforms by team size

The bigger the team, the more often marketing owns the site.

Team size (people)	Homepages	Next.js	Webflow	Framer	WordPress
0 to 5	1,699	718	150	102	40
6 to 15	706	198	158	69	38
16 to 50	385	105	120	33	30
51 or more	154	39	47	11	12
16 or more, 2024 to 2026 batches only	77	28	19	11	0

Source: Pentaclay YC website study, 10 Oct 2026. Team size as listed in YC’s public company data; companies with no number count as 0 to 5. One company has no usable team size and is left out, so the rows add up to 2,944 of the 2,945.

How much AI crawlers can read

We fetched about 80 homepages per platform again as GPTBot, OpenAI’s crawler. We read the raw HTML without running JavaScript and counted the visible words.

Platform	Homepages tested	Median words AI crawlers can read	Fewer than 50 words
Single-page app (Lovable, Bolt and similar)	77	8	64 of 77
Lovable (its own code found)	23	8	16 of 23
Next.js	79	724	2 of 79
Webflow	78	1,136.5	2 of 78
Astro	77	1,174	0 of 77
Framer	80	1,543	1 of 80

Source: Pentaclay YC website study, crawler test on 10 Oct 2026.

What 114 AI company homepages show a customer

AI-tagged YC companies in B2B, fintech, health and industrials, with 16 to 530 people, from the 2021 to 2025 batches. Fetched 13 Oct 2026.

On the homepage	Homepages	How we counted
A link to a security, trust or compliance page	66 of 114	A link to /security, /trust, /trust-center or /compliance, a trust or security subdomain, or a link labeled “security” or “trust”.
A link to customers or case studies	75 of 114	A link to /customers, /case-studies, /stories or /success, or labeled “customers”, “case study” or “customer stories”.
A link with “demo” in its label	74 of 114	Link text contains “demo”.
A link to a pricing page	58 of 114	A link to /pricing or /plans, or labeled “pricing”.
An llms.txt file	64 of 114	/llms.txt answers with a text file longer than 50 characters.
Mentions integrations	77 of 114	Text contains “integration” or “integrate”.
Says “docs” or “documentation”	61 of 114	Anywhere in the text, menu labels included.
Mentions SOC 2	38 of 114	“SOC 2” or “SOC2”.
Mentions GDPR	31 of 114	“GDPR”.
Mentions HIPAA	19 of 114	“HIPAA”.
Mentions SSO, SAML or single sign-on	16 of 114	Any of the three.
“AI” in the main headline	42 of 114	The H1 contains “AI” or “artificial intelligence”.
Calls the product “AI-powered”, “AI-native” or “AI-driven”	39 of 114	Any of the three.
No main headline (H1) in the HTML	16 of 114	No H1 with text in it.

Source: Pentaclay audit of 114 YC AI company homepages, 13 Oct 2026. Text means the homepage HTML without scripts and styles.

Sign-up, demo and pricing

How each homepage lets a customer start, and whether it links to pricing.

What the homepage offers	Companies	Link to pricing
A sign-up and a demo	39	33 of 39
A demo, no sign-up	37	17 of 37
A sign-up, no demo	13	6 of 13
Neither	25	2 of 25

Source: Pentaclay audit of 114 YC AI company homepages, 13 Oct 2026. Sign-up means a link such as “sign up”, “get started”, “start free”, “try free” or “free trial”. Demo means “contact sales”, “talk to sales”, or a link to request, book, get or schedule a demo.

AI agent companies and control

57 of the 114 homepages mention agents three or more times. Here is what those 57 say about control.

Of those 57 homepages	Count	How we counted
Mention human review, oversight or approval	20 of 57	“Human in the loop”, “human review”, “human oversight”, “approval” or “approve”.
Mention an audit log or trace	13 of 57	“Audit log”, “audit trail”, “full audit”, “full trace”, “traceable” or “every action”.
Mention guardrails	7 of 57	“Guardrail”.
Mention none of the three	31 of 57

Source: Pentaclay audit of 114 YC AI company homepages, 13 Oct 2026.

How we ran the study

Which companies

We started from the public YC company list (the yc-oss dataset). We kept every company from the 2021 to 2026 batches with a website: 3,791 sites.

How we fetched

We fetched each homepage once on 10 Oct 2026, as a normal desktop browser. We didn’t crawl other pages. 2,945 answered with a page. 817 failed, mostly bot protection and dead domains, and 29 came back empty.

How we named the platform

We looked for each platform’s own code in the HTML: framerusercontent.com for Framer, website-files.com for Webflow, /_next/static for Next.js, and so on. When a site builder and a framework both show, the builder wins. 495 of the 2,945 had no sign we could name.

Single-page apps

A “single-page app” loads one JavaScript bundle from /assets/index-…, the pattern Vite builds leave. Lovable, Bolt and similar AI builders make this kind of site. The group also has some React apps that teams wrote by hand, mostly in the 2021 and 2022 batches. Homepages with Lovable’s own code count on their own: 23 of them.

The AI crawler test

We took about 80 homepages per platform and fetched them again as GPTBot. We read the raw HTML without running JavaScript, as AI search crawlers do, and counted the visible words. Google runs JavaScript, so a site can rank on Google and still look empty to ChatGPT, Claude or Perplexity.

The 114 AI homepage audit

We took AI-tagged YC companies in B2B, fintech, health and industrials with 16 or more people: 86 B2B, 15 fintech, 7 health and 6 industrials. We fetched each homepage on 13 Oct 2026 and checked it with the text and link rules in the tables above.

Limits

846 of the 3,791 homepages couldn’t be read, so some companies are missing. YC leans toward US, technical founders, so other startups may build differently. A homepage is one page: a company may have a security page its homepage doesn’t link to. The text rules count words, not quality.

What it means for founders

Small teams write their own site, and that’s fine. 718 of 1,699 teams of 0 to 5 people run Next.js.
When marketing joins, the site changes hands. At 16 to 50 people, Webflow leads with 120 of 385. Pick the platform by who will edit the site after launch.
If an AI builder made your site, check what AI search sees. On 64 of 77 single-page homepages, AI crawlers could read fewer than 50 words.
Link your security page from the homepage. 66 of 114 AI company homepages do, and 38 mention SOC 2.
Give each customer a way in. 39 of 114 offer both a sign-up and a demo, and 33 of those 39 link to pricing.
Say what the product does before you say it’s AI. 39 of 114 homepages call the product AI-powered, AI-native or AI-driven.

Questions about the study

Can’t find your answer?

Book a call and let’s talk.

Or email us at contact@pentaclay.com

What do YC startups build their websites with?

Next.js is the most common platform: 1,060 of the 2,945 homepages that answered. Webflow is next with 475, then Framer with 215. It changes with size. At 16 to 50 people, Webflow leads with 120 of 385.

Can ChatGPT read a website built with Lovable or Bolt?

Often very little. AI crawlers read the raw HTML and don’t run JavaScript. In our test, 77 client-rendered single-page homepages showed them a median of 8 words, and 64 of the 77 showed fewer than 50. Framer homepages showed a median of 1,543.

Do funded startups still use Webflow?

Yes, once they grow. Webflow runs 120 of 385 homepages at companies with 16 to 50 people, and 47 of 154 at 51 or more. New batches use it less: 14 of 648 homepages in the 2026 batch.

How many AI companies link a security page from their homepage?

66 of 114 in our audit of YC AI company homepages with 16 or more people. 38 of the 114 mention SOC 2, and 16 mention SSO, SAML or single sign-on.

How did you work out each site’s platform?

We fetched each homepage once and looked for each platform’s own code in the HTML. 495 of the 2,945 had no sign we could name, so they count as unknown.

Can you check our website the same way?

Yes. Send us your website for a Free Website Audit. In 3 business days, we’ll tell you what’s missing and what to fix, including how much of it AI crawlers can read.

Our services, and more to read.