Url Checker is an Android application developed by TrianguloY that acts as an intermediary step towards opening URL links. It is a small, free, and ad-free app that uses as few permissions as possible (only the internet permission) and is available on GitHub for users to suggest and add new modules.

The app consists of a modular setup that allows users to enable or disable individual modules. The Input Text module displays the current URL and can be edited manually, while the History module allows users to view and revert any changes made by other modules or edits from the user. The Status Code module retrieves the status code of a URL and displays it, and the VirusTotal Analysis module allows users to scan URLs using VirusTotal and check the report. The Clear URL module removes referral and useless parameters from the URL, and the Pattern module checks the URL with regexp patterns that warn, suggest, or apply replacements.

Other modules include the Debug module, which displays the intent URI and info about the ctabs service, and the Open module, which contains the open and share buttons. The app is useful when opening an external link from an email, social network app, or similar.

Overall, Url Checker is a light-sized and efficient app that is especially useful for those who need to open external links frequently.