We have this to consider, by downloading a Diagram Designer you can open it in a text editor, and you can edit your text. Edit your text is the key here. You can save your file in several formats including PDF, HTML, and perhaps Microsoft Excel. You have a complete control of all the tools you are able to edit the files you save. The next thing you want to consider is, there is no charge at all. Free software.
The application has a calendar. It is easy to use. Your design or diagram can be downloaded to your PC from the internet. You can send your file via e-mail.
Your download is available as a zip file. It comes with a video tutorial that explains everything that you need to know. You can make a diagram from any subject, it does not matter. If you want to make a diagram on a particular subject. All you need to do is make a blank PDF file, then you will be given the option to use the default font of a big company, or you can use one of many fonts that you want to use. Also, you can modify it in the size of what you want it to be.