I haven't found the ultimate all-in-one source for everything picth accent yet. Tell me if you ever find it though. Really, please do. All I have is a piecemeal approach with several sources, each of which fill at least part of my pitch needs :)

• NHK日本語発音アクセント辞典
  My go-to pitch accent source is the NHK Japanese Pronunciation Accent Dictionary. There's a book version originally released in 1998 but I like it digitally. There's an app for both Android and iOS. Even better though, and that's actually what I'm doing, all text entries are available on the net. For example one kind soul put an export in the form of a plain text comma-separated values (CSV) file into the Anki add-on Japanese Pronunciation / Pitch Accent. Downloading the add-on gives you the file nhk_pronunciation.csv with roughly 116,000 entries and their pitch accent markers straight from the book/app. Apparently the fellow who provided the CSV file also has a Github repository with a similar version, though that one has 102,000 entries for some reason. I didn't bother closely comparing both files. All I know is that the CSV file taken from the Anki add-on has the data I want 8 times out of 10. On a side note, word on the street is that there's also an EPWING-formatted version out there but I've never seen it myself.

• accent.u-biq.org
  This one's more of an appetizer. Doesn't hold much data but can supplement the NHK dictionary in some cases. For example the NHK dictionary doesn't say anything about 日米 or the city of ローマ, both of which I found at U-biq.

• Online Japanese Accent Dictionary
  This one has a metric fuckton of pitch accent data for adjectives and verbs and their conjugations. I'm way too beginner to tell if it's anywhere near exhaustive but let's just say I nearly shat myself when I found the site. Not only is each word marked with standard Tokyo pitch accent markers, they also all have voice samples by a gal and a guy. Plus variations if they're noteworthy. It's apparently a project by a professor at the University of Tokyo, hence the u-tokyo.ac.jp domain.

• Wadoku
  和独辞典 is a Japanese-German dictionary. Probably not all that useful for in-depth info but can fill in gaps that aren't addressed by the above-mentioned sources. Has accent markers for about 60% of its entries. Of course, unless you wanna bother with German you still need translations/definitions from someplace else :) But still.

//edit
Thought I'd post a preview of the kind of data you're getting at each place.

• NHK辞典

• U-biq

• OJAD

• Wadoku