customer.io

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customer.io is ranked #2,285 in the Tranco list of the world's most popular websites (list of Oct 13, 2026), down 72 places in four weeks. The domain was registered on Oct 26, 2011, 14 years, 11 months ago, through 1API GmbH, and is paid up until Oct 26, 2026. Its homepage uses Next.js, React and Google Tag Manager. It is served through Vercel.

Global rank

#2,285

▲ 5 this week

Domain age

14 years

since Oct 26, 2011

Technologies

detected on the homepage

SEO score

96/100

homepage checks

Popularity rank

#2,285 of the top 1 million sites in the Tranco research ranking, which averages several traffic and DNS sources over 30 days. Best rank in the period shown: #2,158.

Weekly Tranco rank (lower is more popular).

See where customer.io sits in the top 10,000

Domain registration

Registered: Oct 26, 2011 (14 years, 11 months ago)
Expires: Oct 26, 2026
Registrar: 1API GmbH
Name servers: ns-1181.awsdns-19.org, ns-1893.awsdns-44.co.uk, ns-499.awsdns-62.com, ns-618.awsdns-13.net
DNSSEC: Not signed

From the registry's public RDAP record, checked Oct 1, 2026.

Technology stack

JavaScript frameworks

Next.js React

Analytics

Google Tag Manager

Hosting

Vercel

Detected from the homepage HTML and response headers on Oct 14, 2026. Tools loaded only after scripts run (or after consent banners) may be missing.

Homepage SEO check

Checked from the HTML our scanner received on Oct 14, 2026. Content added later by JavaScript isn't counted.

96/100

https://customer.io/

Customer.io: Customer Engagement Platform For Better Outcomes

Customer.io is a customer engagement platform for creating personalized journeys and better business outcomes across email, push, SMS, and in-app messaging.

21 passed · 2 warnings · 0 failed

Content

✓Title61 characters
✓Meta description156 characters
✓H1 headingExactly one H1
✓Subheadings7 H2 headings
✓Image alt textAll 85 images have alt text
✓Content lengthAbout 549 words

Indexing

✓IndexableNo noindex directive
✓Canonical URLhttps://customer.io
✓robots.txtFound
✓XML sitemapFound
✓Language attributeen
✓Structured dataOrganization

Social sharing

✓Open GraphTitle, description and image set
✓Twitter / X cardsummary_large_image

Technical

✓HTTPSServed over HTTPS
✓Mobile viewportFound
✓FaviconFound
✓Character encodingutf-8

Security headers

✓Strict-Transport-SecuritySet
✓Content-Security-PolicySet
!Clickjacking protectionNot set
✓X-Content-Type-OptionsSet
!Referrer-PolicyNot set

Server response

Final URL: https://customer.io/
HTTP status: 200
Server: Vercel
Response time: 1.66 s (first byte 1.61 s, from our scanner in a US data centre)
HTML size: 479 KB
Compression: br

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#695	optimizely.com	Next.js, React, Vercel
#1,479	cpmstar.com	Next.js, React, Vercel
#2,043	mparticle.com	Next.js, React, Vercel
#2,154	revenuecat.com	Next.js, React, Vercel
#2,648	webrootcloudav.com	Next.js, React, Vercel
#2,837	cloudx.io	Next.js, React, Vercel

Sites ranked near customer.io

Rank	Website	Registered	Built with
#2,280	messenger.com	1998	—
#2,281	telefonica.de	—	Nginx, jQuery
#2,282	example.org	1995	Cloudflare
#2,283	purdue.edu	—	WordPress, Google Tag Manager, Adobe Fonts
#2,284	im-apps.net	2013	Google Cloud Storage
#2,286	a-mx.com	2021	—
#2,287	amazonaws.com.cn	—	React
#2,288	quantummetric.com	2011	Next.js, React, Vercel
#2,289	unruly.co	—	WordPress, WP Engine, Cloudflare
#2,290	aibixby.com	2018	—

Questions about customer.io

How popular is customer.io?

customer.io is #2,285 worldwide in the Tranco list published Oct 13, 2026.

How old is customer.io?

customer.io was registered on Oct 26, 2011, which makes the domain 14 years, 11 months old.

What is customer.io built with?

We detected Next.js, React, Google Tag Manager and Vercel on its homepage.

Who is the registrar of customer.io?

1API GmbH, according to the registry's RDAP record.