This is a very small PHP script to recognize and display Unicode characters that are otherwise invisible.
The tool's target group are software developers and others who step over strange issues when handling text/data inputs. These may be inputs from users, server responses or database contents that the own scripts do no handle as expected. If the reason is not obvious when looking at the input, it may be caused by Unicode characters that are typically invisible.
We decided to share the tool's source code on GitHub, because the online tool received some attention, and users may have reasonable privacy concerns when uploading data to external websites. The online tool is available and can be used without installation at www.soscisurvey.de/tools/view-chars.php.