Altmetric Blog

Interactions: The Numbers Behind #ICanHazPDF

Jean Liu, 9th May 2013

icanhazpdfA while ago, I wrote about the ways that people use Twitter to share scholarly articles but one thing we didn’t cover is the use of hashtags. Most tweets are sent to share the paper that is mentioned, and so it follows that most hashtags describe a personal reaction or highlight a notable aspect of the paper. However, a question from James Hardcastle inspired us at Altmetric to look into the use of one particular hashtag – #icanhazpdf (or “I Can Haz PDF”). This hashtag indicates the someone is requesting, rather than sharing, a paper – as such, it completely changes the intent of a tweet. Because #icanhazpdf tweets also contain links to papers we’ve been tracking them for a while as a side effect of our work for publishers and institutions.

#icanhazpdf originally arose as a more efficient way for science journalists and bloggers (who generally lack institutional access to journals) to quickly obtain PDF versions of scholarly articles. The process is simple: requesters tweet a link to the paywalled article along with the #icanhazpdf hashtag. Other users then respond to the request by retrieving the PDF through their own institutional access and e-mailing the file to the requester. Once the PDF has been received, the requester deletes his or her original tweet.

Rightly or wrongly using #icanhazpdf infringes copyright, but its practice is fiercely defended by many. As such, the hashtag has been the subject of many heated online debates surrounding the legality and morality of the practice (see comments in the previous link). I won’t be commenting on the legal or ethical issues of #icanhazpdf, but I would like to point out some interesting usage pattern data from the Altmetric database.


The usage of #icanhazpdf

I took a look at #icanhazpdf data from Twitter that Altmetric collected over 12 months, between May 2012 to April 2013 (see data on figshare). The graph below (Figure 1) is a timeline showing the number of #icanhazpdf tweets per week.

Figure 1

Figure 1. #icanhazpdf requests from May 2012 to April 2013

In this data set, the number of #icanhazpdf tweets peaked at 55 a week early this year (week 38, 16th January 2013), but was only 6 immediately after Christmas last year (week 35, 26th December 2012). Although this snapshot of activity is only over 12 months it seems as if the overall usage of the hashtag is slowly increasing. Over the time period examined, we saw a total of 1314 tweets tagged with #icanhazpdf. This came to about an average of 3.6 #icanhazpdf tweets per day, and 25.3 tweets per month.

What’s interesting here is the fact that there are actually not very many Twitter requests in the grand scheme of things. Compare 1314 #icanhazpdf tweets in 1 year to the roughly 10,000 tweets with links to papers (both closed- and open-access) that are seen by Altmetric per day.


The who and where of #icanhazpdf

Who is using #icanhazpdf? I took a random sample of 100 tweeters who had used the hashtag between May 2012 and April 2013 and categorised them by occupation/role by looking at their Twitter user profiles (see anonymised data on figshare). The categories were: Academic (including scientists, post-docs, and research fellows), Business (those affiliated with a commercial organisation), Communicator (including journalists and bloggers), Community, Librarian, Public, Student (undergraduates and graduates), Teacher, and Unknown (not listed or unclear from profile). The pie chart below (Figure 2) shows the breakdown of a sample of 100 tweeters according to occupation/role.

Figure 2

Figure 2. Occupation/role breakdown out of 100 users

The chart suggests that academics (35%), students (24%), and communicators (16%) use #icanhazpdf the most. This isn’t exactly surprising, since it’s been clear from online debates and conversations that it’s these groups of people that tend to defend the usage of #icanhazpdf in spite of copyright infringement issues. Interestingly, even though the hashtag was created with communicators in mind, it appears to have been embraced by a high number of academics and students. These groups presumably have access to certain journals already, and previously might have employed more closed means of obtaining articles (e.g., e-mailing the author or colleagues from other universities). However, the fact that the #icanhazpdf request goes out to complete strangers from all over the web is probably the most appealing factor, since casting a wider net would presumably increase the likelihood of catching the desired paper.

Figure 3

Figure 3. Geographic breakdown out of 100 users

Another interesting insight from the chart is that communities and members of the general public do not frequently request papers with #icanhazpdf. One might have expected that members of the public (notably patient communities), who would only be able to read open-access journals, would be more likely to use such a method to obtain paywalled papers. A possible explanation for the low usage of the hashtag is the lack of awareness amongst members of the public. The hashtag was used in the online science journalism community before it later spread to associated academics and their respective networks. Now, the usage of #icanhazpdf appears to be growing, which is perhaps due to an increase in awareness in different online communities. As such, it will be interesting to continue to follow the hashtag’s usage.

In some regions of the world institutions may have limited access to journals, despite publisher driven initiatives like HINARI. Might there be higher usage of #icanhazpdf in third-world countries? In order to find out where #icanhazpdf requesters were based, I categorised the same 100 tweeters based on the location they listed in their Twitter profiles. The bar chart on the right (Figure 3) shows the geographic breakdown within the sample. Nearly half of the #icanhazpdf requesters originated from the US, but a large number also came from Great Britain. The low levels of #icanhazpdf usage in other countries could be due to a variety of factors, including, again, lack of awareness of the hashtag.


The value of qualitative data

If tweets are tagged with #icanhazpdf, then what are the implications for altmetrics and (of particular interest to us) the Altmetric score? #icanhazpdf tweets could potentially complicate new metrics that characterise tweets too broadly – “sharing” tweets certainly signal something different to others that are effectively saying “I haven’t read it, but want to”.

Altmetric LolcatHowever, if you step away from reputation metrics and think in terms of attention instead, then the bias of #icanhazpdf doesn’t matter as much. The act of requesting a PDF still reflects attention (just as sharing a link to an abstract would). Attention is what the Altmetric score is meant to gauge: irrespective of whether the intent is to share or to receive, Altmetric treats an article mention of any kind as a signal of attention.

Since the average daily number of #icanhazpdf tweets is low (3.6 per day according to data from the past year), I would argue that the potential effects of #icanhazpdf tweets on altmetrics data isn’t a huge concern for the vast majority of papers. For qualitative assessments, it’s easy to view the Twitter conversations themselves within article details pages. As always, instead of relying on the numbers alone (e.g., “12 tweeters” for a single article) it’s important to review the qualitative data and adjust impressions about uptake and impact accordingly.

The effects of #icanhazpdf on altmetrics are arguably negligible at the present time, but its mere existence opens up interesting questions about research uptake. For example, is asking for a paper a more certain sign of uptake than sharing the article to people who lack access to the journal? It may just be a simple tag, but it certainly adds another layer of complexity to altmetrics.

A sincere thank-you goes to Bora Zivkovic, blogs editor for Scientific American, who shared many valuable insights with me over a phone conversation, and HT to James Hardcastle for the inspiration.

50 Responses to “Interactions: The Numbers Behind #ICanHazPDF”

Nico (@nfanget)
May 9, 2013 at 12:00 am

I understand it is #icanhazpdf "etiquette" to delete the tweet once the PDF has been received, would that lead to an under-estimation of the numbers?

It is not surprising to see very low incidences in non-English speaking countries, where the "I can haz" meme is meaningless.

Ross Mounce (@rmounce)
May 9, 2013 at 12:00 am

The total number of #icanhazpdf tweets seems a bit low to me...

Given the official etiquette is to delete the #icanhazpdf tweet once you receive the PDF you want... I'm wondering whether your analysis here is really sampling *all* the tweets that were sent out? Could it be that your count is only of non-deleted #icanhazpdf tweets. Is it possible that the true sum of #icanhazpdf tweets could be much greater?

Euan Adie
May 9, 2013 at 12:00 am

Yes and no. We capture the great bulk of tweets in realtime via streaming - there are edge cases where we miss tweets because (1) it takes us a few hours to pick some others up or (2) because there's a backlog with processing them on our end and they've been deleted in the intervening period, but those don't significantly change the numbers.

The numbers are lower than I expected too and they must be dwarfed by people swapping papers by email etc. but an interesting question is perhaps do you know of any hashtags used by scientists that are *more* popular over a sustained period of time?

Clari (@clarileia)
May 30, 2013 at 12:00 am

Given that the standard etiquette is to delete these tweets after you've got the paper, does the fact that you're archiving them (& publicising that you're archiving them) act as a possible deterrent to people using the hashtag and/or twitter to ask for it? Could your archives be requested to prove copyright infringement?

August 10, 2013 at 12:00 am

@jcsouto Sim. Já consegui alguns asssim. Um link que explica

October 10, 2013 at 12:00 am the numbers behind icanhazpdf #altmetric

Find scientific papers the easy way | AoB Blog
November 28, 2013 at 12:00 am

[…] The Lazy Scholar extension adds a button to the right of the omnibox. When you hit a paywall you can click the button and LazyScholar will use Google Scholar Search to see if it can find a full text version of the article for you. The search is over the whole web, so it stands a good chance of finding it if it’s in an institutional repository, a personal repository or a file that someone has craftily stored somewhere. As far as getting a paper goes, it can be a lot quicker than #icanhazpdf. […]

Sibele Fausto (@sibelefausto)
December 10, 2013 at 12:00 am

@anneclinio uai, cê não conhece? Veja o excelente post da @portablebrain:

March 6, 2014 at 12:00 am

I wasn't even aware this #scholarly #access through Twitter was a thing - #latetothecoversation

March 11, 2014 at 12:00 am

@smakelainen perhaps you could try the ICanHazPDF hashtag? (

[…] read. What do you want to find out about? Then head to Google Scholar and use the icanhazpdf hashtag to get hold of the […]

Ian McCullough
April 18, 2014 at 12:00 am

Interesting. I've been getting higher numbers while keeping track of this.

April 23, 2014 at 12:00 am

Looking for a paper that's behind a paywall: use the #ICanHazPDF hashtag.

Graham Steel (@McDawg)
April 23, 2014 at 12:00 am

Interactions: The Numbers Behind #ICanHazPDF by @portablebrain

April 30, 2014 at 12:00 am

Nice analysis of #IcanHazPdf tag

Graham Steel (@McDawg)
June 17, 2014 at 12:00 am

@bat__go Ha. Thanks. Guess this kinda ties in with

June 30, 2014 at 12:00 am

TIL: "I Can Haz PDF" exists. Pretty cool stuff.

August 11, 2014 at 12:00 am

@leilaluheshi try #icanhazpdf?

Graham Steel (@McDawg)
August 12, 2014 at 12:00 am

@christlet You might be interested in this...

August 14, 2014 at 12:00 am

@quantombone try title and link to paper with hashtag icanhazpdf

August 14, 2014 at 12:00 am

More people in the Siggraph and IEEE communities need to learn about the hashtag "icanhazpdf":

Phill Jones (@phillbjones)
September 18, 2014 at 12:00 am

.@acochran12733 mentioned #icanhazpdf. Relevant blog post: #sspfall14

Lindsay Allen
September 18, 2014 at 12:00 am

James Hardcastle's Twitter is

Graham Steel (@McDawg)
September 27, 2014 at 12:00 am

@eperlste From May 2013, Interactions: The Numbers Behind #ICanHazPDF by @altmetric's @portablebrain

October 21, 2014 at 12:00 am

@botperrier mode d'emploi de Twitter :

November 6, 2014 at 12:00 am - the stuff you find out when you go to a conference

November 20, 2014 at 12:00 am

"Rightly or wrongly using #icanhazpdf infringes copyright, but its practice is fiercely defended by many." #opened14

January 15, 2015 at 12:00 am

Interactions: The Numbers Behind #ICanHazPDF

January 16, 2015 at 12:00 am

Interactions: The Numbers Behind #ICanHazPDF

March 23, 2015 at 12:00 am

Have you thought about looking at other categories quantitatively to explore additional qualitative input? For example, looking at retweets vs. original tweets (or responses vs. queries) could theoretically give you a more detailed account of who's helping and who's looking (professionally, geographically, etc.). However, I don't have a personal sense of the data - if you accounted for retweets and/or responses that included the hashtag, my above suggestion would be of little concern. I'm glad to see this post - I think #icanhazpdf is a fantastic tool for many!

June 9, 2015 at 12:00 am

@mrgunn @sshreeves can capture the tweets with the streaming api like altmetric did for this

[…] A pesar de todas estas normativas y limitaciones legales, el uso de este hashtag ha aumentado en los últimos años como bien demuestra Jean Liu en un artículo del blog […]

Graham Steel (@McDawg)
August 8, 2015 at 12:00 am

"Interactions: The Numbers Behind #ICanHazPDF" (2013) by @portablebrain

James Hardcastle (@JwrHardcastle)
August 12, 2015 at 12:00 am

@shanemcanning @AdamCommentism there was an @altmetric blog post in 2013 there might be more current posts around

[…] those that don’t know about the hashtag #icanhazpdf, see the likes of this, this (PDF) and […]

August 18, 2015 at 12:00 am

@carolafrediani some literature exploring #IcanhazPDF requests

Digital Science (@digitalsci)
August 18, 2015 at 12:00 am

From the @Altmetric archive - The Numbers Behind #ICanHazPDF

Graham Steel (@McDawg)
September 6, 2015 at 12:00 am

@Mcarthur_Joe Couple that come to mind are from @portablebrain & also

[…] Liu, J. (2013). Interactions: the numbers behind #icanhazpdf. Disponible via […]

[…] community by posting publisher versions on sites such as and ResearchGate or using the #icanhazpdf hashtag on Twitter. All of this seems to go on with impunity, apart from an occasional flurry of […]

[…] open access happening on Twitter. I read an article this morning about a hashtag called #icanhazpdf. Academics are requesting PDFs they don’t have access to from academics that do using this […]

October 26, 2015 at 12:00 am

Another interesting look at icanhazpdf, #gned2402

Graham Steel (@McDawg)
November 11, 2015 at 12:00 am

@astonsplat @blahah404 The most recent stuff that I know of was by @portablebrain in 2013

Graham Steel (@McDawg)
November 11, 2015 at 12:00 am

@davidecarroll @astonsplat @chartgerink @blahah404 Fair comment. Data should be anon. as before

Lupicinio Iñiguez (@lupicinio)
December 5, 2015 at 12:00 am

Interactions: The Numbers Behind #ICanHazPDF #openaccess

January 3, 2016 at 12:00 am

A little analytics on the papers being shared via #icanhazpdf
#openaccess #springerlink

January 4, 2016 at 12:00 am

The #icanhazpdf furor? Tempest in a teakettle if is right; amounts to only 3 requests/day.

Graham Steel (@McDawg)
January 6, 2016 at 12:00 am

@biolumiJEFFence The most recent study is at (PDF), earlier work at

[…] I am a member of ResearchGate; it is supposed to be a scientist-only social network, perhaps a “Facebook for Science” (as Eli Kintisch wrote in 2014 in Science‘s Career Magazine), in which scientists can upload and share their research papers, track citations, follow the work of – and even request papers from – colleagues and fellow scientists across the world. Every once in a while I receive requests for some of my papers, usually from institutions in South America, India, and so on. ResearchGate allows me to upload my papers to their system for easy sharing with researchers who ask for them. It’s a formalized and organized way of sharing research articles evocative of the #IcanHazPDF hashtag on Twitter. […]

Jensen Malerfirma
April 5, 2022 at 12:00 am

So many great resources here! Very useful for research purposes. So awesome, thank you.

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