# What does CHECK24 use? CHECK24 (check24.de) shows public evidence of 27 tools, according to runsonwhat (last checked 2026-10-18). - Industry: Financial Services - Size: 1,001–5,000 employees - Based in: München, Germany - Founded: 1999 - LinkedIn: https://www.linkedin.com/company/check24-vergleichsportal-gmbh ## Edge & Hosting | Tool | Category | Evidence | Since | |---|---|---|---| | [Cloudflare](https://www.runsonwhat.com/reverse/cloudflare) | CDN & Edge | Custom domain | 2025-09 | | [Amazon CloudFront](https://www.runsonwhat.com/reverse/cloudfront) | CDN & Edge | Custom domain | | ## Application | Tool | Category | Evidence | Since | |---|---|---|---| | [React](https://www.runsonwhat.com/reverse/react) | Frontend | Website code | | | [Tailwind CSS](https://www.runsonwhat.com/reverse/tailwind) | Frontend | Website code | | | [Anthropic](https://www.runsonwhat.com/reverse/anthropic) | AI | DNS verification records | | | [OpenAI](https://www.runsonwhat.com/reverse/openai) | AI | DNS verification records | | | [Twilio](https://www.runsonwhat.com/reverse/twilio) | Backend & Database | DNS verification records | | | [Remix](https://www.runsonwhat.com/reverse/remix) | Frontend | Website code | | ## Data & Observability | Tool | Category | Evidence | Since | |---|---|---|---| | [Google Analytics](https://www.runsonwhat.com/reverse/ga) | Analytics | Website code | | | [Google Tag Manager](https://www.runsonwhat.com/reverse/gtm) | Analytics | Website code | | | [Sentry](https://www.runsonwhat.com/reverse/sentry) | Monitoring | Website code | | | [PagerDuty](https://www.runsonwhat.com/reverse/pagerduty) | Monitoring | Custom domain | | ## Go-to-market | Tool | Category | Evidence | Since | |---|---|---|---| | [Google Ads](https://www.runsonwhat.com/reverse/google-ads) | Ads & Pixels | Website code | | | [Microsoft Ads](https://www.runsonwhat.com/reverse/bing-ads) | Ads & Pixels | Website code | | | [Zendesk](https://www.runsonwhat.com/reverse/zendesk) | Support & Docs | Email records | | ## Company Ops | Tool | Category | Evidence | Since | |---|---|---|---| | [Microsoft 365](https://www.runsonwhat.com/reverse/microsoft-365) | Workspace | Email records | | | [SendGrid](https://www.runsonwhat.com/reverse/sendgrid) | Email Delivery | Email records | | | [Apple Business](https://www.runsonwhat.com/reverse/apple) | Workspace | DNS verification records | | | [Atlassian](https://www.runsonwhat.com/reverse/atlassian) | Dev Tools | DNS verification records | | | [Proofpoint](https://www.runsonwhat.com/reverse/proofpoint) | Security & Compliance | Email records | | | [Mailgun](https://www.runsonwhat.com/reverse/mailgun) | Email Delivery | Email records | | | [DocuSign](https://www.runsonwhat.com/reverse/docusign) | Finance & Legal | DNS verification records, Website code | | | [Slack](https://www.runsonwhat.com/reverse/slack) | Collaboration | DNS verification records | | | [Have I Been Pwned](https://www.runsonwhat.com/reverse/hibp) | Security & Compliance | DNS verification records | | | [Jamf](https://www.runsonwhat.com/reverse/jamf) | Security & Compliance | DNS verification records | | | [Cursor](https://www.runsonwhat.com/reverse/cursor) | Dev Tools | DNS verification records | | ## Recent changes at CHECK24 - 2026-10-18: stopped using [EasyDMARC](https://www.runsonwhat.com/reverse/easydmarc) ## FAQ ### What tools does CHECK24 use? As of October 2026, runsonwhat has found 27 tools at CHECK24 (check24.de) in public records. Edge & Hosting: Cloudflare and Amazon CloudFront. Application: React, Tailwind CSS and Anthropic. Data & Observability: Google Analytics, Google Tag Manager and Sentry. Go-to-market: Google Ads, Microsoft Ads and Zendesk. Company Ops: Microsoft 365, SendGrid and Apple Business. Last checked October 18, 2026. ### What email provider does CHECK24 use? CHECK24 uses Microsoft 365 for email and office software, alongside Apple Business, according to runsonwhat (October 2026). runsonwhat found Microsoft 365 through email records that authorize Microsoft 365. Microsoft 365 is used by 704,051 companies runsonwhat tracks. ### What does CHECK24 use for customer support? CHECK24 uses Zendesk for customer support and documentation, according to runsonwhat (October 2026). runsonwhat found Zendesk through email records that authorize Zendesk. Zendesk is used by 41,062 companies runsonwhat tracks. ### What analytics tools does CHECK24 use? CHECK24 uses Google Analytics for analytics, alongside Google Tag Manager, according to runsonwhat (October 2026). runsonwhat found Google Analytics through Google Analytics code on check24.de. Google Analytics is used by 855,765 companies runsonwhat tracks. ### What monitoring tools does CHECK24 use? CHECK24 uses Sentry for monitoring, alongside PagerDuty, according to runsonwhat (October 2026). runsonwhat found Sentry through Sentry code on check24.de. Sentry is used by 77,142 companies runsonwhat tracks. ### How long has CHECK24 used Cloudflare? CHECK24 has used Cloudflare since at least September 2025, going by the first public certificate of the check24.de subdomain that points at Cloudflare. ### Does CHECK24 use Cloudflare? Yes. runsonwhat found Cloudflare at CHECK24 through a subdomain that points at Cloudflare, in use since at least September 2025. Cloudflare is a CDN & Edge tool used by 693,813 companies runsonwhat tracks. ### Does CHECK24 use AI tools? Yes. runsonwhat has found Anthropic and OpenAI at CHECK24; Anthropic, for example, through a DNS verification record for Anthropic. AI services called only from servers leave no public trace, so CHECK24 may use more AI tools than these. ### Has CHECK24 changed tools recently? Yes. On runsonwhat's rechecks, CHECK24 stopped using EasyDMARC (latest on October 18, 2026). A change counts only between two checks of check24.de done the same way. ### Which companies have a tech stack similar to CHECK24's? The companies with the stacks most like CHECK24's are Reflex, Convera, DOKU and Salary Finance, according to runsonwhat (October 2026). Each shares 6 to 13 tools with CHECK24, and rare tools count for more than common ones like Google Workspace, so the match reflects real stack choices. ### How does runsonwhat know what CHECK24 uses? runsonwhat reads public records only. Of the 27 tools at CHECK24, 11 were found through DNS records, 8 through code on check24.de, 5 through email records and 3 through subdomains that point at the vendor. A tool is listed only when a direct record backs it up; DNS is rechecked weekly and check24.de about monthly. --- Source: runsonwhat, https://www.runsonwhat.com/company/check24.de (updated October 2026). Counts are companies with direct public evidence of the tool (DNS records, certificates, website code, a real-browser crawl, subprocessor lists), so they are lower bounds. Methodology: https://www.runsonwhat.com/methodology.