Pdf annotator alternative Archives

I won't really write much about it for one reason which is a big deal: while you can highlight text, you can't leave notes. Nearest functionality is 'recommending' a highlight while reading a comment, but that's only displayed on your 'timeline'.

Pocket API doesn't support exporting highlights too, or to be precise it seems to be hidden. If you need it you can use my script where I hacked around it.

Also, interesting enough, Kobo reader has got Pocket integration, but for some reason when you read Pocket articles on Kobo, you can't highlight at all (let alone syncing highlights with Pocket). Not sure what's the purpose of this integration.

Pocket was acquired by Mozilla in 2017, which might be a good thing, but so far their main focus seem to be readability features.

You can also read a rant raising similar issues to what I mentioned.

I won't go into Instapaper's readability capabilities (e.g. fonts and article formatting) because it's not something I care much about, so you might be better off googling that for yourself, here I'll concentrate on annotating aspect. Here are couple of recent extensive comparisons of Instapaper and Pocket, which feature screenshots and other aspects of Instapaper:

So, to read something in Instapaper, first you'll have to import the article into it (to unclutter and optimize it for reading). Due to this import process, you can only read and highlight in Instapaper's app, and you can only see your highlights there as well, which is its main limitation for me.

The only reason I'm using it at all is that its Android app has got offline capabilities, so I would export to Instapaper things I want to read on the tube while I don't have connection and read/comment while offline.

Mind that free version of Instapaper has got 5 notes per month limit. Personally I'm happy to pay 3$ per month for premium version of such a decent product though in absence of good alternatives.

Instapaper got Json API, through which you can access your saved articles, comments and highlights. I'm using a fork of python wrapper to access it. Highlights are only stored as text though (as opposed to CSS/xpath locators), so there is no easy way to match them against original text apart from some sort of fuzzy search.

Search function works for full text search in saved articles, but doesn't let you restrict search for highlights, and you can't search in notes at all.

One red flag was in 2018 when Instapaper wasn't available in Europe for few months until they resolved GDPR issues. While I don't blame it on Instapaper, this is a kind of thing that happens when you don't own your data and use a closed source product.

Wallabag is the most mature open source/selfhosted read-it-later kind of project I know of. Here's a review featuring some screenshots of their web app and Android app.

It's very similar to Instapaper in terms of having to import the article in Wallabag in order to annotate it. I used it for a while and only had some issues with importing articles heavy on MathJax backed Latex.

If you don't want to selfhost it, you can use wallabag.it hosting for as little as 9 euros per year and two weeks of trial.

There is also an Android app, but sadly it lacks support for highlighting.

I wish it had more attention from the community, and might try to work on Android annotation when I got more time.

Hypothesis is simply awesome and my favorite web annotation tool. Their killer feature is that it embeds a bit of JS in the page to provide an in-browser overlay, so you don't have to leave the page you were reading and can highlight and add comments natively. They use something cool called fuzzy anchoring to achieve this. That also makes annotations resilient to document markup changes, and if they can't locate your annotations it would be still shown in metadata as 'orphaned', so you never lose your notes.

Another cool feature is that you can choose to make your annotations public and see other people's annotations or create a private group if you want to share them among specific people only.

To get a sense of it you can skim through tutorial which has plenty of screenshots, and I also strongly recommend you checking it out in action here: Annotation Is Now a Web Standard, or try the very page you're reading now.

You don't have to install anything or register, it's just a widget embedded in the page, but do make sure to allow JS. You should see yellow highlights and the sidebar on the right.

It's open source, can be selfhosted and they provide their own service for free (but please consider donating them!).

Since Hypothesis powered by javascript, it actually works well in modern Android browsers via bookmarklet. It's somewhat not obvious in terms of browser UI how to actually use them though:

• for mobile Firefox, once you added a bookmarklet, to invoke it you need to tap on the address bar and click the bookmarklet.
• for mobile Chrome, it's a bit more tedious but also possible.

One downside of this service is that you won't be able to annotate while offline. I feel it's actually more of mobile browser's problem in general rather than Hypothesis though. While you potentially can annotate offline without querying API and preserving data in , if you can't load the page in the first place, it doesn't matter. Perhaps that can be given better support in browsers.

Hypothesis got JSON API which gives access to your and other people's public annotations. I'm using judell/Hypothesis python wrapper to access and back up this data.

Shameless plug! If you just want to send annotations directly into a plaintext (e.g. org-mode) file and don't really care about displaying them within the original web page you can use my grasp browser addon for that.

I typically use it for highlights that would be good candidates for TODO items, e.g. something actionable like piece of advice or further reading.

Not available for mobile yet, but perhaps on Android native select and share capabilities (e.g. into orgzly) makes more sense anyway.

Hypothes.is is a clear winner for me on desktop and I'm using Instapaper for offline reading on Android.

Probably most widely used PDF readers, all of these use Poppler library for working with PDF, which in particular does the messy business of annotation handling.

All of them would let you view existing annotations, but there are some nuances and limitations:

• Atril (as of 1.20.3) allows you to add or edit popup notes only, other types of annotations aren't even displayed in the sidebar

• Evince (as of 3.32.0) only allows to add or edit highlights or popup notes (no inline!). Here is article with some screenshot (not much changed since 2016).

  However it's got a nasty few years old bug (1, 2) that doesn't allow you saving over the same file you're editing. That means that to work around it every time you want to persist your changes, you'd have to save to a new file and reopen the new copy. That makes it pretty unusable unless you only want to do couple of changes.

• Okular (as of 1.6.3) allows editing and adding pretty much every type of annotation that you would expect: highlights, popup and inline notes, freehand and more.

  Annotation process (screenshot) is pretty pleasant, hitting Ctrl-S results in saving the file you're working on without any problems.

  Okular also got support for something called 'document archive', which saves the original document in a zip file along with , which allows you to annotate non-PDF files (e.g. DJVU), which is a very neat feature. It's obviously Okular specific, in theory though it's possible to process with other tools.

  Search in okular can't be restricted to annotations only and while you can use normal PDF search for inline notes and highlights (along with the other text that happened to match), it doesn't work at all for popups.

  Even though Okular is part of KDE, there is no reason not to use it in other desktops environments, it's not that complicated in terms of UI; looks quite native in GTK, and few extra dependencies are barely a problem these days.

Pdf-tools (as of 0.90) is a PDF viewer for Emacs that meant to be more efficient than the builtin one (in terms of rendering), but is also capable of interacting with PDF metadata.

Here's a screenshot and a short screencast, interesting stuff starts somewhere around 02:00 mark.

One big drawback is that to highlight and add new annotations you still have to use mouse, which loses half of the benefits of using Emacs for me. Also it's got some minor issue displaying inline annotations text in the 'Content' buffer and annotations list (you can edit it if you click on it with your mouse though).

There are few other apps I tried using so figured it's worth mentioning.

• mupdf (as of 1.14.0) is both rendering library (claimed to be faster than poppler) and PDF viewers. It's capable of displaying all types of highlights and annotations, but there is no way to add or edit them.

  It mentions annotation editing in changelog, but in something called 'mupdf-gl', and it doesn't seem to be available in Ubuntu.

• zathura (as of 0.4.3) is capable of both poppler and mupdf backends, but suffers from the same problem that you can't edit and add new highlights. It's pretty sad, because I like it as a viewer: it's minimalist and capable of VI style keybindings.

Org-noter (as of 1.3.0) allows you to annotate a PDF while keeping the text annotations in a separate file which keep track of PDF locations in Org note properties. Here's a short demo.

For me the main drawback is that it doesn't let you highlight, which I tend to do a lot.

Existing annotations in PDF can be imported via function (it didn't work for me for some reason though, and I wasn't motivated enough to investigate).

Xournal is different from the above PDF viewers, since it isn't using types of annotations described in the PDF standard and instead uses its own tools.

It doesn't modify the original files and instead keeps file containing the metadata and pointing at the original PDF, so in that sense it's pretty similar to okular. Similarly, it's xournal-specific and can't be viewed anywhere else unless you export it in PDF before sharing (at which point your annotations wold basically become background images).

Already mentioned in the previous section, it's also capable of annotating PDFs via pdf.js.

Check out their guide, especially if you're using Chrome, apart from it it's as easy as opening the PDF in your browser and activating Hypothesis. It fingerprints the PDFs so you don't have to worry about losing your annotations and it's easy to collaborate with other people.

It seems to work fast enough for big PDF books as well, however generally reading long things in browser is not very convenient as you lose reading position if you close the tab.

Polar is a new project which aims to be not just reader, but 'personal knowledge repository'.

• supports highlights and comments
• document repository, so you have overview of all the stuff you ever read/commented. It also keeps track of your reading position.
• the PDFs are fingerprinted, so you don't need to worry about moving them around your filesystem
• directory holds all the data, which makes it easy to share among your computers (e.g. via git, or if you keep it on Dropbox and symlink)
• metadata is in well structured files, which makes it easy to access from scripts
• highlight locators keep matched text alongside the absolute coordinates, which leaves potential for matching against different editions of the PDF file
• it's got builtin flashcards engine. Personally, I'm too used to org-drill now, but that's a great a way of introducing spaced repetition to people.
• the author is very passionate about this project, invests a lot of effort and quite ambitious

If you like it, please consider donating them!

The only downside is that annotation format is Polar specific, so it'd be hard to share with other people unless they are willing to use Polar as well.

Similar disclaimer: I've never had Iphone, so have no idea what people use. If anyone sends me a link to a decent overview, I'd be happy to include it!

• Adobe Reader

  Supports most reasonable ways of annotation: highlights, popup/inline comments, strikethough, styling, etc. (screenshot). "Comment List" gives overview of your document: screenshot.

  It offers Adobe Cloud and Dropbox integration, but I rely on Syncthing for syncing my stuff anyway.

• Xodo

  Basically supports same things that Adobe does.

  For me, Xodo wins by a very thin margin because its interface tends to be a bit more denser and 'material': interface, annotations list. Otherwise, it's virtually no different from Adobe Reader.

• mupdf

  The F-droid description claims it supports annotation, but it couldn't display any of the existing ones in my pdf files. What's more, the app wasn't responsive on any long taps or my attempts to select text, let alone highlight or comment.

  Perhaps PDF 1.7 is too outdated? Something weird has been going on with the 'full' version, maybe this is somehow related (1, 2).

• Pen&Pdf: I tried this one since it was open source and claimed to support annotation, but it didn't even manage to pick up any of the existing ones.

If you want the convenience of editing and viewing on phone and working with other people, Okular wins on desktop and Adobe Reader/Xodo could be used on your phone.

If you care about preserving the original PDF files and want convenience in accessing the annotations programmatically, Polar is the best.

Kindle stores bookmarks, notes and highlights in on the device. The good thing about the format is that it's already plaintext and fairly human readable, so you might be happy with that alone. The format is a bit nasty for parsing (as you would expect from something with extension). Dates are locale dependent, document locators may or may not have roman numerals, separators are inconsistent at times, etc. When I was using Kindle I was just copying the file from time to time, and you can set up some sort of automatic copying when your device is connected similarly to what I'm doing with Kobo.

Kindle uploads your notes and highlights to Kindle Cloud Reader (screenshot, screenshot) , but it only works for stuff bought on Kindle store. Reportedly people also have issues displaying their highlights on Cloud Reader due to copyright restrictions.

Kindle also integrates with Goodreads, which synchronizes reading progress and lets you selectively share annotations to Goodreads. But that's also restricted to books bought from Amazon.

Search function is somewhat limited: you can search in the book and it displays your highlights alongside content it found in the book, but you can't restrict search to highlights. You can't search in notes either. Funny enough though, the file can be opened on Kindle itself (as any other file), and then you can search in it. It's not super convenient, but better than nothing. (I wasn't brave enough to try and see what happens if you try to highlight in this file.)

Stores all of it's stuff in on the device.

The database has got lots of cool stuff: in addition to highlights and notes you can also access reading progress, time spend reading and possibly some other interesting data I didn't manage to reverse engineer yet. You can check out kobuddy, which is my attempt to extract useful data from the database and provide nicer high level Python interface. It's also fairly straightforward to open it in and play with your own queries.

I'm using kobuddy as well to work around it.

There is an official Android app which lets you manage and annotate books from Kobo store and seems to be syncing progress between eink and phone. However annotations don't sync between Kobo and phone for me, and other people also report same experience: 1, 2, 3. Some claim it works on iphones though.

Kobo lets you conveniently search over all of your highlights and notes.

Koreader is an alternative open source software for Kindle, Kobo and other E-ink devices.

It's got some very cool features, in particular most common document formats, dictionary and Wikipedia lookups, and various plugins.

It also supports highlighting, but (as of v2019.06), note taking is unsupported yet, but some progress is going on. I'd be keen to try it once it's implemented!

So far, for me the only downside of using nice tools for annotating digital content is that it ruined the experience of reading paper books for me.

Usually I don't own the books I read, so using a highlighter or pencil would be just mean to the owner. Even if you own the book and okay with that, it's still not searchable and not easily accessible, which feels very wrong to me.

To get around this I've tried few of tricks:

• Take pictures of bits I'm interested in, perhaps highlight using image editor on the phone
• Sticky notes are ok for commenting as long as you don't damage the book with the glue, but they down help with highlighting

• Using paper strips as an annotation overlay.

  This one I'm particularly proud of coming up to as I haven't found anyone else doing that, and I rarely come up with useful meatspace things.

  This is how it looks in action: photo.

  Basically, before reading, I prepare a bunch of paper strips slightly longer than the page height, kinda like bookmarks. You will use it as a 'sidebar overlay' for writing notes and highlighting, so the width depends on your handwriting and how much you're expected to do that, I usually use something like 1/4 of the page.

  If you want to annotate the page, you'll align strip's bottom to the bottom of the page and mark lines you found interesting on this strip and write comments on it as well. You can also use the other side of the strip to annotate the other page.

  The downside of this is that in order to annotations to make sense, it requires a physical copy of exact same book. Another one is that it doesn't have automatic timestamps, which somewhat bothers my #lifelogging OCD. You can get around it by writing down time as well, but that's quite distracting.

When I'm done with a book, I'd spend a bit of time digitizing annotations and manually typing them into plaintext. Luckily, I don't have to do that often.

Often, I want to leave a quick comment to an org-mode item. I've got a handy Emacs binding which appends a child note with a timestamp and enters edit mode, so the whole process is smooth. If you're not using org-mode you still can benefit from something similar, most of modern text editors allow you binding snippets on hotkeys.

One big drawback with Org mode (and I believe most of outline/task list formats) though is that if you insert child outline items in the middle of text, it would structurally break it in two parts, so you'd have to append your commend to the end of current outline (which can be potentially very long). On the other hand, plain list items, which you can insert in arbitrary place, are very limited and don't support most of things outline support like tags, timestamps, priorities etc.

Often when I watch lectures or some talks on Youtube or in VLC, I want to leave a bookmark or write a note with a reference to a specific timestamp. This is pretty much not possible apart from opening your text editor and manually recording the position in video. All the video annotation software I know of is more oriented towards video editing/effects etc.

So, if I'm watching something in browser, I normally end up using grasp and manually type the timestamp.

This is distracting, but even worse is that whatever you use have no means of quickly jumping to the timestamp you recorded; you'd have to move the slider to it manually.

There is no common standard that I know of for jumping at a certain timestamp neither in web nor in desktop applications (e.g. via mime handler).

I'd say this is somewhat unsolved problem, which is surprising since presumably it could be helpful for lots of students.

Due to the lack of common standard for annotated content, some services try to implement their own:

• Medium. They use highlights and annotation that also serve social function: when you read a Medium post you can see if a certain bit of text was highlighted by many other people.

  They don't tamper with browser selection, so you can still use external annotation tools like Hypothesis. However, judging by their API, there is no way to access your highlights. Anyway, I would encourage people not to use these especially if you only care about personal use, after all Medium is not the only source of information out there.

• Genius. Annotated lyrics on genius.com looks neat, however I'm not sure what are its benefits over Hypothesis.

  Also, while I was looking up about Genius, I've stumbled upon an unusual opinion opposing web annotation: how to block Genius annotations:

  Genius was functionally equivalent to forcing crude, violent, or hateful user comments onto a web site she created as a safe space to write about the sensitive work she does

  I can't agree with this, but I think it deserves to be mentioned.

These are tools suggested by other people, I haven't had time to try them all properly yet, but will list nevertheless. If someone sends me links to other people's experience with these, I'd be happy to add them!

• org-emms: org-mode link handler to start playback at certain timestamp, could potentially be useful for video annotation:

  [[emms:/path/to/audio.mp3::1:10:45]] Starts playback at 1 hr 10 min 45 sec.
• Incremental video in SuperMemo: could be useful for video annotation. Suggested by Ypo.

• Readwise: paid (30 day trial) web tool that allows you to import and sync your highlights from Kindle/Instapaper/Pocket/Medium/etc so you could review them later via daily emails or web app. They've got a nice blog where they are describing how to use spaced repetition and read actively.

  Suggested by few people, in particular Daniel, one of the cofounders.

  UPD from [2019-12-21]: I gave it a try and it's actually pretty neat. They send you an email daily so you can practice spaced repetition with a single link click. Personally I'm too invested in all of my own infrastructure, but if you want to try out spaced repetition without extra hassle, I highly recommend checking it out!

• Skim: open source PDF reader and note-taker for OS X. Uses xattrs and a separate file to keep annotations.

  Recommendation from a follower.

• Kontxt: paid, looks very similar to Hypothesis, also offers some sort of CMS. I couldn't find anything on it on Reddit/Hackernews, not sure if it's still under development.
• Histre: also looks similar to Hypothesis in terms of web annotation, also enhances browser history. Here's HN discussion.

• Hook productivity: paid MacOS tool that allows to interlink content between different apps.

  Suggested by Luc P. Beaudoin.

• Worldbrain Memex: free, offline first tools that works similarly to Hypothesis as well and provides some browser history enhancements. I really need to looks closer into that one!

  Recommended by Jay.

• VideoAnt: looks like video annotation tool. Suggested by philyg.

• Microsoft OneNote: can be used for PDF annotation, but it seems that you have to import PDF in OneNote first, so it'll become locked in the app. However that allows extra features like using pen to annotate on top of PDF. In that regard it's similar to Xournal.

  Suggested by daok.

These are services that wouldn't let you select text. Not sure why that happens: could be some sort of copyright restriction, being assholes, or just accidental pointless restriction.

• Facebook: Android app and mobile site prevent text selection.

• Blinkist: Android app and website.

  You can't use native text selection as Blinkist forces some custom JS for highlighting. But their highlights suck: you can't leave a comment and also they actively prevent you from selecting text forcing to use their own JS thing.

  In addition you can't even export your highlights, best you can do seems to be syncing to an Evernote notebook, and perhaps then you can use Evernote API. I didn't bother with it though.

  UPD (20190818) I actually managed to dump my highlight data before canceling Blinkist subscription by using (apparently private) API, here's the script.

I'm only listing tools that support proper highlighting and commenting.

As a specific example how I do it: recently my friend asked me if I could recommend them posts I found interesting on Slate Star Codex. With a tiny python script I was quickly able to give them some stats on posts I read, so they could choose among them.

I've got bunch of scripts and a rendering tool which I named orger (yep, haven't invested that much thought into naming). Basically, these scripts take specific data source as input and produce org-mode output, e.g. renders backed up from Instapaper into file. That runs every few hours and keeps the contents relatively up to date.

I chose org-mode as I was already used to its features, keybindings and metadata. Also the hierarchy (e.g. book → highlight → comments) fits naturally into outline format. But not that it's a real necessity, I feel that as long as it's searchable plaintext, it's good enough.

To search them, I've got a global keybinding, which invokes Emacs with incremental search prompt against the directory with rendered files, which lets me interact with them in a blink on my computer. On Android I'm using DocSearch indexer (sadly it's not incremental, and app is not open source, so I'm looking for alternative). I describe this extensively here.

Finally, I've got a Recoll indexer instance + web interface running on my VPS; so if necessary I can access and search annotations via the internet.

While reading, I often encounter something I want to google or check or read about later; or just come up to something actionable inspired by what I'm reading. But I also don't want to interrupt from reading and losing context: that especially matters while reading on a E-ink device: distracting from the book, fetching your phone etc is really annoying.

So, as a workaround, I have programmed rules that pick out notes that start with "TODO" or marked with "TODO" tags; etc, and they are automatically added to my agenda. Later, when I see it on agenda, I'd assign it a priority and reschedule/unschedule depending on importance.

Here's an example of me using using module for that.

I'm writing about it in more detail in post about Orger.

It's kind of an extension of the previous use case: again, often you want to send something straight into your spaced repetition queue without having to remember to add that.

I've got two rules for that:

• if something is annotated with a certain marker ('drill' for me, comes from org-drill package name)
• if it's only got one word highlighted, which is useful for memorizing foreign words

Here's how I'm using it for Kobo highlights.

I'm a big fan of #lifelogging and all the timestamped highlights, comments and reading progress from Kobo are an effortless (no manual logging!) contribution to my personal timeline, which I render and sync on my devices every few hours.

I sometimes use it when conversation with other people comes to awkward silence, so I can recall something I was reading recently and spark off an interesting (well at least for me) topic.

• 2019-12-02: added section with suggestions by other people.