Frequently Asked Questions

This is a collection of questions I've had directly from users, or questions I thought you might want to know about.

FAQ for Open Access Helper for Safari and Open Access Helper for iOS

Who are you?

My name is Claus Wolf and I have successfully developed and deployed PHP & JavaScript based applications for libraries for the last 7+ years. I will be the first to admit that I am not a great developer, but I have the pleasure to know that my apps are used by hundreds of institutions - although they wouldn't know ;)

These days I work for a company operating in the "library space", but this application is my hobby project and as such isn't affiliated with my employer.

Why did you develop this?

To be honest, I simply wanted to have a play to learn how a Safari App Extension would work. The development documentation is a bit light and I needed a real project to truly learn stuff. When I came across the rather useful Unpaywall API and their Google Chrome & Firefox extension, I was a bit sad that it wasn't available for Safari. I quickly realized that I could build a super simple clone and make it available for free... Free is the right price, as the extension itself doesn't do much and all the magic comes from the excellent service.

I created the iOS App, since I felt a bit sorry that all the Open Access goodness was for desktop users only and just like with the Safari App Extension, I wanted to learn how a Safari Action Extension and Share Extension should be programmed. It's fun to learn new things...

How do you test?

I created a document with test cases and their expected outcome, every release is tested against that document. You can access it here...

What languages are supported?

macOS: English & German
iOS: English & German
Please contact me, if you would like to help translate the app into more languages

What about privacy?!

macOS: Privacy is really important and the extension ask for some really "wild" permissions. So let me try and explain what the app actually does:

  1. When you navigate to a website and the page loads, a simple JavaScript (JS) file is injected
  2. The JS initially determines, whether it is in an iFrame (or not)
  3. If the script isn't in an iframe, it attempts to find a Digital Object Identifier (DOI) on the page.
  4. If a DOI is found it executes a call to API (this happens within the App component of the extension in Swift)
  5. If knows the DOI and has an Open Access location on file, a metadata object is returned, which has the location of the article. At this point an orange icon is injected on the page and the toolbar icon is given an exclamation mark badge. You can either click the orange button or the icon to acces the document
  6. In the background the app will follow (again within the extension) the URL (which often is to to identify the actual final location. Based on some simple logic it checks on whether you might be on the Open Access document already. If so, the icon changes to green and the toolbar icon gets a checkmark badge
  7. At no point, do I or one my servers get any of your data - that's a promise. But don't take my word for it. As there isn't much secret sauce here, please feel free to review the code at GitHub

macOS: v1.2 you will be able to highlight text within a website and then use the context sensitive menu to start an Open Access search in:


macOS: v1.7 - we now also support Discovery Search

  • If did not have information, we'll check
  • will only receive the DOI of the document you are looking for
  • You can disable this feature in settings

macOS: v1.8 - we now support sending a request to the author via

  • When using this feature, a blue badge is shown, whenever we couldn't find an Open Access Copy
  • Only if you click this button, the URL of the page will be sent to
  • When using the service, please refer to their privacy policy
  • You need to enable this feature in settings

iOS: The design of the Safari Share / Action Extension makes it less "problematic", but still I would want you to know what happens:

  1. When you select the OA Helper icon from the Share Sheet or Action Extension, a simple JavaScript (JS) file is injected
  2. The JS initially attempts to find a Digital Object Identifier (DOI) on the page.
  3. If a DOI is found it executes a call to API (this happens within the App component of the extension in Swift)
  4. If knows the DOI and has an Open Access location on file, a metadata object is returned, which has the location of the article. At this point I add that information to a UIView and display it to you, giving you a clearly labelled button to either cancel or access the document
  5. At no point, do I or one my servers get any of your data, unless you elect to share these with me (default). But don't take my word for it. As there isn't much secret sauce here, please feel free to review the code at GitHub

iOS: v1.5 - you have the ability to enable several settings, to support Bookmarks, iCloud Syncing & Sharing of statistics, here is what you need to know

  • The iOS will locally keep a record of the number of Open Access Alternatives Found, Searches conducted, PDFs viewed an the number of bookmarks.
  • If you opt in to sharing these with me, they will be shared (along with a UUID) with me once a month
  • If you opt in to use bookmarks, these are stored within Core Data on your device
  • If you opt in to use iCloud Sync, these are stored within your private iCloud database, to which neither I nor any other developer have access
  • You can remove your opt in within the settings app at any time

iOS: v1.8 - we added support for Discovery

  • As with macOS Version we will check with if did not know an Open Access document
  • Only the DOI is used for the API call
  • You can disable this feature in Settings by selecting Only use

iOS: v2019.10 - Support for Article Requests & improved settings

  • You can enable this feature in Settings by selecting Open Access Button Request
  • If enabled, we will present a button, if clicked it sends the URL to
  • Before providing your details, please review their privacy policy

iOS: v2019.12 - CORE REcommender

  • You can enable this feature in Settings by selecting Show Similar Articles
  • If enabled, we will present a table with up to three article recommendations beneath the action buttons

The extension cannot find Open Access for a specific article, can you help? covers > 23 million Open Access documents [25 December 2018], but there obviously are many more. The App will also check Discovery and thus will have covered most sources available. Lastly, if you enable it, you can use to ask the author to make their work avaialble by posting it online in a legal and copyright compliant way.

Maybe your document just isn't known, yet? Try searching BASE,, DOAJ or Google Scholar, or speak to your library's info desk. Library staff are oustanding at finding content and if there is no Open Access, they might be able to help you with an Inter Library Loan for less than what the publisher is asking for.

Another option is that the extension could not extract a DOI on the page. I am trying to be quick and nimble and thus look for certain meta-tags on the page, rather than look at all the content with a regular expression.
macOS Users: If you are ever in doubt, open the Developer Console (⌥+⌘+i) - I "print" a few bits there quite clearly :)

macOS: Why does the icon not turn green, even though I am at the full text

Sometimes you are at an Open Access location, but reports a different location. Open Access is great, but often has more than one place to access a document.

Sometimes the code that follows the link gets to one place and stops and then "sees" two different domains, for example "" vs ""

macOS: Why does it take a second or two for the icon to turn green is fast, but the code that follows all the redirects to determine, whether we are at the "final" location, depends on your internet speed and the number of redirects and the speed at which those servers respond.

Why should I trust you?

You really shouldn't trust anyone on the internet. If you know how to read a little JS and Swift, please review the macOS code on GitHub - it ain't rocket science! You probably will want to check on these two files first:

The source code for the iOS app can be found here

Safari App Extensions and iOS Apps are pretty great and have a lot of solid features to protect your privacy, but in the end you need to decide, whether you wish to trust the extension or not. At the time of writing nothing in the code actively logs you or your browsing behavior. To make it obvious the extension does stuff, the toolbar icon will change, while the extension is active. The iOS App makes even fewer calls.

Liar, Liar, Pants on Fire:
if you don't track me, how can you show me the number of Open Access articles found?!

For the macOS App, one of the things the app does is keep a counter of how many Open Access versions it found - or rather how often the orange button was injected. This is done locally and I don't get that info, even though I would love to have it ;) It is a simple text file named count.txt and you can find it in ~/Library/Group\ Containers/_MY_TEAM_ID.otzshare/Library/Caches

For iOS similar values (OA Searches, OA Found, PDF, Number Bookmarks) are kept on device and if you opt in to do so, will be shared with me once a month. The values themselves are integers which are useful to understand which area of the app needs further development.

Why on earth did you decide to collect certain data and make it shareable (iOS)?

The data I collect was designed to be useful to you the user. What's the value of the app, how many Open Access Documents did you find. How many Open Access Searches did you conduct? How many PDFs did you view? It isn't meant to track you.

Without any data and pretty much without feedback, it has been hard to know what to focus on in development. I thus decided to ask you for your opt in to get some of these values. If you don't opt in, nothing is shared. If you do opt in, only these integers are shared, along with a UUID (unique ID). However that unique id is unique to you and my app and not your phone, thus I won't ever be able to sell the data or know who you are. Even if I wanted to sell the data, all I have is a few integers.

How do you make money?

Some really solid advice for anything on the internet is: follow the money. If you don't pay for something, you are likely the product.

  • The advice is right, yet I am doing this as a hobby, so the truth is: I am NOT making any money through the app
  • Like yourself, I have a full-time job that pays the bills. It is a pretty fun job and it pays reasonably well, so I don't need the app to make money
  • The app wouldn't work without, so I feel that charging even a dollar would be unfair
  • If you don't pay, I don't owe you anything either. Thus, if you find a bug, report it - but no guarantees.
  • My wife said it was ok for me to spend €99 / year for the developer account. She loves me and thus doesn't realize that I shouldn't be trusted with money. If you don't tell her, I won't either.
  • Maybe you do want to send me a few dollars, just to say thank you? In that case, I suggest you give it someone, who needs it more. If you truly can't think of anyone, click this link for a great organization, which will do wonderful work with your money (but they need more than a dollar at a time)

What the heck is a Otzberg?

Otzberg is the name of the "mountain" overlooking the village in which I live. When I lived in the US I started the habit of using this as my screen name on various services. When the opportunity arose I licensed and the rest is history. Wikipedia has a pretty extensive article in German and English, check it out :)


With any questions, you can reach me at:

Claus Wolf
Am Hergert 1
64853 Otzberg
oahelper [at]

Download free of charge

Open Access Helper is available for macOS and iOS. Try it now and make better use of Open Access!

macOS Download iOS Appstore