runsonwhat

Castle's tech stack

What does Castle use?

Castle (castle.io) uses at least 30 tools we can see from public records, including Netlify for hosting, Intercom for customer support, PostHog for analytics and Ghost for its website. Last checked .

“A complete suite of SDKs and APIs to monitor users, block bots, and stop in-app fraud.”

Industry
Security
Size
11–50 employees
Based in
San Francisco, United States
LinkedIn
Company page
Re-check liveVisit castle.io
Tools found
30
Categories
16
Layers
5 of 5
Last checked
Nov 2026

Castle's stack, layer by layer

Of 30 tools, 11 came from website code, 7 from DNS verification records, 7 from custom domain and 5 from other records. Each tool links to the other companies we've found using it. The label says what kind of public trace gave it away.

Edge & Hosting

5 tools, where the bytes are served from

Hosting & Cloud

CDN & Edge

DNS

Application

3 tools, what the product is built with

Frontend

AI

Data & Observability

6 tools, what they measure and store

Monitoring

Analytics

Go-to-market

7 tools, how they find and keep customers

Website & CMS

Marketing

Ads & Pixels

Support & Docs

Company Ops

9 tools, what the team runs on day to day

Email Delivery

Workspace

Collaboration

Dev Tools

Security & Compliance

Companies like Castle also use

Tools common among companies with a similar stack that we haven't found at Castle.

Companies with a stack like Castle's

Ranked by shared tools, with rare tools counting more.

Castle tech stack FAQ

What tools does Castle use?

As of November 2026, runsonwhat has found 30 tools at Castle (castle.io) in public records. Edge & Hosting: Cloudflare, Amazon Web Services and Amazon Route 53. Application: Tailwind CSS and Astro. Data & Observability: Google Analytics, Google Tag Manager and web-vitals. Go-to-market: Google Ads, LinkedIn Insight Tag and ActiveCampaign. Company Ops: Microsoft 365, Google Workspace and SendGrid. Last checked November 13, 2026.

What cloud does Castle run on?

Castle uses Amazon Web Services for hosting and cloud infrastructure, alongside Netlify, according to runsonwhat (November 2026). runsonwhat found Amazon Web Services through Amazon Web Services code on castle.io. Amazon Web Services is used by 147,664 companies runsonwhat tracks.

What email provider does Castle use?

Castle uses Microsoft 365 for email and office software, alongside Google Workspace, according to runsonwhat (November 2026). runsonwhat found Microsoft 365 through a DNS verification record for Microsoft 365. Microsoft 365 is used by 737,877 companies runsonwhat tracks.

What does Castle use for customer support?

Castle uses Intercom for customer support and documentation, alongside ReadMe, according to runsonwhat (November 2026). runsonwhat found Intercom through email records that authorize Intercom. Intercom is used by 9,213 companies runsonwhat tracks.

What analytics tools does Castle use?

Castle uses Google Analytics for analytics, alongside Google Tag Manager, PostHog and Segment, according to runsonwhat (November 2026). runsonwhat found Google Analytics through Google Analytics code on castle.io. Google Analytics is used by 904,335 companies runsonwhat tracks.

What is Castle's website built with?

Castle uses Ghost for its website, according to runsonwhat (November 2026). runsonwhat found Ghost through a subdomain that points at Ghost. Ghost is used by 904 companies runsonwhat tracks.

Does Castle use Cloudflare?

Yes. runsonwhat found Cloudflare at Castle through Cloudflare code on castle.io. Cloudflare is a CDN & Edge tool used by 736,485 companies runsonwhat tracks.

Which companies have a tech stack similar to Castle's?

The companies with the stacks most like Castle's are eAI, Quickwork, Streamlinehq and stakefish, according to runsonwhat (November 2026). Each shares 5 to 13 tools with Castle, and rare tools count for more than common ones like Google Workspace, so the match reflects real stack choices.

How does runsonwhat know what Castle uses?

runsonwhat reads public records only. Of the 30 tools at Castle, 11 were found through code on castle.io, 8 through DNS records, 7 through subdomains that point at the vendor, 3 through email records and 1 through website configuration files. A tool is listed only when a direct record backs it up; DNS is rechecked weekly and castle.io about monthly.

We read public traces only: DNS and email records, certificate logs, website code and published subprocessor lists. A tool is listed when a direct record backs it up, and dropped when a recheck no longer finds it. Is this your company? See how to opt out.