Digital Grimoire?

Literally any text document should suffice. Adobe acrobat, Microsoft Word, Notepad, etc. Depending on what you're looking to do with it. Acrobat will be the most flexible with combing images and text, but if it's just text Microsoft Word will do just fine.

There may also be journaling apps, if that's more your preference.

I personally use Google Docs for mine. It saves automatically and it has some nice customization options that allows you to add in really nice pictures, tables, borders, etc.

I use google drive because you can create a Grimoire folder, and then separate sections with more folders and keep it all organized.

I used a notebook app for a time, I could make different notebooks for different topics, not much in the way of pictures, but it was good for text. I know there are some notebook apps that do pictures as well.

Other apps you might find of interest would be moon phase, astrology, tarot, oracle cards, plant identification, there are also a slew of apps on witchcraft and magic, most are not all that good, but some can be helpful.

I have a digital grimoire. It's called Sorcerous Intrusions & Daemonic Excellence. www.LeftHandSorcery.com

I keep a digital Book of Shadows/Grimoire on my computer and also backed up on a stick drive. Then I can print off the parts I want to put into a hard-copy Book of Shadows. (I'm a belt and suspenders sort of person! )

My computerized version is done on Microsoft Office where I've created a folder for it and then sub-folders for the different topics.

Nice. I keep lots of redundant backups of everything.

Personally I would use a blog with tagging features or something like that, for me it helps with organization and looking back at dates and also reflecting on my old writing without feeling the need to delete. I second everyone saying notes app or document, but if you want to make it public maybe even learning to use and personalize a site like wix, WordPress, Blogger, or even theage old Tumblr. Good luck!

Sounds like a good idea do you know what you want in it?