Ask HN: How do you store your knowledge?

I recently started trying to be better about organizing links, thoughts, PDFs, etc so I can more easily pull things up when I only remember a fragment. So far haven't been able to find a great solution. My requirements are that it caches webpages (and PDFs), supports tags, and has a decent iOS app that syncs to the cloud. Bonus if it has full text search and the ability to upload files not from a URL.

I tried Pinboard and it's pretty good, but the caching is extremely unreliable, the full-text search isn't full-text, and the support is completely unresponsive. I tried historious and it also nearly fits the bill but it doesn't have an iOS app and the bookmarklet doesn't work on PDFs for whatever reason.