
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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200+ free browser tools, most under 40 KB. Lightweight, private and easy to use, with no signup, no intrusive ads and no server-side processing.

Which is more popular?
Based on our record, Cert Decoder seems to be more popular. It has been mentioned 1 time since March 2021.
Website, pricing, platforms and company facts side by side.
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| Website | certdecoder.com | appergo.com |
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| Company | — | 2026 |
| 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.
AppErgo is an independent collection of 200+ free browser-based tools covering text, codes and puzzles, conversions, dates and time, audio, games, random generators, web development and everyday utilities. Available in 10 languages, the website is designed for quick use on desktop and mobile,...
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
How often each product is chosen within a category, 0–100% relative to the other.


As answered by people managing Cert Decoder and AppErgo.
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.
AppErgo's answer:
AppErgo was created in France in 2026 as an independent project developed by a solo creator. Its name combines “App”, for applications and online tools, with “Ergo”, reflecting a focus on ergonomics, simplicity and ease of use. The project started with a small collection of practical tools and gradually grew into a toolbox of more than 200 tools covering text, codes and puzzles, dates, audio, games and everyday tasks.
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
AppErgo's answer:
AppErgo is primarily built with static HTML, CSS and vanilla JavaScript. Its pages are generated through a custom administration system based on PHP and MySQL, while the public tools rely on standard browser technologies such as SVG, Canvas and the Web Audio API. All processing takes place directly in the browser, without external APIs or remote processing services.
Cert Decoder's answer
certdecoder.com is primarily built for developers, sysadmins, cybersecurity enthusiasts, and DevOps engineers.
AppErgo's answer:
AppErgo is designed for students, teachers, developers, creators, office workers, puzzle enthusiasts and everyday users who need a practical online tool without creating an account or navigating a complicated service. Its wide range of tools supports both occasional tasks and regular use on desktop or mobile.
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.
AppErgo's answer:
AppErgo is built for people who want to open a tool, complete a task and move on. It combines more than 200 fast, lightweight and responsive tools with clear interfaces and local browser processing. There is no signup, no intrusive advertising and no unnecessary upload of personal data. The tools are available directly on desktop and mobile, without installing anything.
Cert Decoder's answer
certdecoder.com is primarily built for developers, sysadmins, cybersecurity enthusiasts, and DevOps engineers.
AppErgo's answer:
AppErgo is primarily designed for individual users rather than named enterprise customers. Its audience includes students, teachers, developers, creators, puzzle enthusiasts and anyone looking for a quick browser-based tool.
AppErgo's answer:
AppErgo brings together more than 200 browser tools in one fast, lightweight and privacy-friendly toolbox. Every tool is 100% free, works without an account, runs directly in the browser, avoids intrusive advertising, and is fully responsive on both desktop and mobile.
Share your experience with using Cert Decoder and AppErgo. 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
Tracking AppErgo since Jul 2026.