
Decode and verify SSL/TLS certificates online. Extract X.509 details including issuer, validity, SAN, and fingerprint. Fast, secure, and browser-based.

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Learn Bash, PowerShell, and CMD online through interactive, hands-on labs.

Which is more popular?
CMD Master might be a bit more popular than Cert Decoder. We know about 1 link to it since March 2021 and only 1 link to Cert Decoder.
Website, pricing, platforms and company facts side by side.
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| Website | certdecoder.com | windows-cli.arnost.org |
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| Company | — | Startup from the Czech Republic · 1 - 9 employees · 2025 |
| Listed in |
In their own words, as submitted to SaaSHub.


Cert Decoder is a free online tool that helps you decode X.509 SSL/TLS certificates in PEM format. It instantly shows important information like the issuer, expiry date, SAN entries, and fingerprint. All data is processed locally in your browser, so nothing is ever sent or stored elsewhere.
Windows Command Prompt Hub: Platform Description Windows Command Prompt Hub (windows-cli.arnost.org) is a modern, web-based educational platform designed to help users learn Bash, PowerShell, and CMD online through interactive, hands-on labs. Built with a high-performance tech stack (Next.js,...
What each product offers, as listed by its team.


Possible disadvantages
An editorial look at what each product does well and who it suits.


Overall verdict
Why this product is good
Recommended for
Overall verdict
Why this product is good
Recommended for
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CMD Master Sarge Review
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As answered by people managing Cert Decoder and CMD Master.
Cert Decoder's answer
I built certdecoder.com over the weekend for my own needs. Sometimes in my work, I need to verify and check certificate details.
CMD Master's answer:
The platform was born from the realization that "passive learning doesn't build muscle memory." Recognizing that students often struggle to retain practical knowledge just by watching videos or reading manuals, the creators set out to replace boring documentation with short, engaging, hands-on missions where learners can make mistakes and learn in a risk-free environment.
Cert Decoder's answer
certdecoder.com was built using just JavaScript and HTML—simple, fast, and with all processing happening locally in your browser, so no certificate data is sent to any server
CMD Master's answer:
Next.js: This powerful React framework forms the core of the frontend architecture. It enables fast page loads, seamless routing, and a highly responsive user interface necessary for maintaining the smooth performance of the in-browser terminal emulator.
Firebase: Serving as the backend infrastructure, Firebase securely manages user authentication and utilizes its real-time database capabilities to store and sync gamification data, such as learner progress, completed missions, and achievements.
Cloudflare: This handles the edge network, providing robust CDN (Content Delivery Network) routing, DNS management, and strict security measures to ensure the platform remains blazing fast, highly available, and protected globally.
GSAP (GreenSock Animation Platform): This industry-standard animation library drives the rich, interactive visual elements on the platform. It brings the UI, terminal feedback, and gamification rewards to life with smooth, high-performance animations that keep learners engaged.
Cert Decoder's answer
certdecoder.com is primarily built for developers, sysadmins, cybersecurity enthusiasts, and DevOps engineers.
CMD Master's answer:
The primary audience consists of aspiring IT professionals, junior system administrators, DevOps beginners, and developers worldwide who want to master essential command-line skills, fast-track their careers, and build a strong foundation for advanced enterprise scripting like PowerShell.
Cert Decoder's answer
Simple, fast, and reliable. Some similar tools can’t even decode basic certificates. I rigorously tested my tool with many real-world certificates and covered several edge cases where competitors fall short.
CMD Master's answer:
Unlike traditional learning methods that rely on dry, confusing system documentation or lengthy, passive video tutorials, Windows Command Prompt Hub provides a 100% safe, isolated sandbox directly in the browser. It allows users to learn by doing with real-time feedback, step-by-step validation, and hints, ensuring they build actual muscle memory without the risk of damaging their own operating system.
Cert Decoder's answer
certdecoder.com is primarily built for developers, sysadmins, cybersecurity enthusiasts, and DevOps engineers.
CMD Master's answer:
Since Windows Command Prompt Hub is an independently developed educational platform, it does not publicly disclose specific corporate enterprise clients or B2B contracts. Instead, its biggest customer segments consist of individual learners and IT professionals, primarily including:
These groups utilize the platform's interactive sandbox to safely build practical muscle memory for their daily technical tasks and career advancement.
CMD Master's answer:
Interactivity. It completely replaces passive observation with an active, hands-on approach. The fail-safe sandbox environment ensures that users get instant validation and feedback the moment they type a command, guiding them interactively through complex scenarios.
Share your experience with using Cert Decoder and CMD Master. For example, how are they different and which one is better?
Recommendations tracked on public social media and blogs since March 2021.


Why? Because I built certdecoder.com and couldn’t find a decent place to submit it. So I said screw it — I’ll build my own. With blackjack and hookers. - Source: dev.to / over 1 year ago
CMD Master is a free online interactive learning platform for the command line. Practice Windows CMD, PowerShell, and Bash in a live browser terminal with instant feedback — no install and no VM. Most lessons are free. For a structured... - Source: dev.to / 3 days ago