Minification vs the GPL

A not-entirely-theoretical question about open source software licensing came up at work the other day. I thought it was interesting enough to warrant a quick dive into the philosophy of minification, and how it relates to copyleft open source licenses. Specifically: does distributing (only) minified source code violate the GPL?

If you’ve come here looking for a legally-justifiable answer to that question, you’re out of luck. But what I can give you is a (fictional) story:

TheseusJS is slow

TheseusJS is a (fictional) Javascript library designed to be run in a browser. It’s released under the GPLv3 license. This license allows you to download and use TheseusJS for any purpose you like, including making money off it, modifying it, or redistributing it to others… but it requires that if you redistribute it you have to do so under the same license and include the source code. As such, it forces you to share with others the same freedoms you enjoy for yourself, which is highly representative of some schools of open-source thinking.

Screenshot showing TheseusJS's GitHub page. The project hasn't been updated in a year, and that was just to add a license: no code has been changed in 12 years.
It’s a cool project, but it really needs some maintenance this side of 2010.

It’s a great library and it’s used on many websites, but its performance isn’t great. It’s become infamous for the impact it has on the speed of the websites it’s used on, and it’s often the butt of jokes by developers: “Man, this website’s slow. Must be running Theseus!”

The original developer has moved onto his new project, Moralia, and seems uninterested in handling the growing number of requests for improvements. So I’ve decided to fork it and make my own version, FastTheseusJS and work on improving its speed.

FastTheseusJS is fast

I do some analysis and discover the single biggest problem with TheseusJS is that the Javascript file itself is enormous. The original developer kept all of the copious documentation in comments in the file itself, and for some reason it doesn’t even compress well. When you use TheseusJS on a website it takes a painfully long time for a browser to download it, if it’s not precached.

Screenshot showing a website for the TheseusJS API. It's pretty labyrinthine (groan).
Nobody even uses the documentation in the comments: there’s a website with a fully-documented API.

My first release of FastTheseusJS, then, removes virtually of the comments, replacing them with a single comment at the top pointing developers to a website where the API is fully documented. While I’m in there anyway, I also fix a minor bug that’s been annoying me for a while.

v1.1.0 changes

  • Forked from TheseusJS v1.0.4
  • Fixed issue #1071 (running mazeSolver() without first connecting <String> component results in endless loop)
  • Removed all comments: improves performance considerably

I discover another interesting fact: the developer of TheseusJS used a really random mixture of tabs and spaces for indentation, sometimes in the same line! It looks… okay if you set your editor up just right, but it’s pretty hideous otherwise. That whitespace is unnecessary anyway: the codebase is sprawling but it seldom goes more than two levels deep, so indentation levels don’t add much readability. For my second release of FastTheseusJS, then, I remove this extraneous whitespace, as well as removing the in-line whitespace inside parameter lists and the components of for loops. Every little helps, right?

v1.1.1 changes

  • Standardised whitespace usage
  • Removed unnecessary whitespace

Some of the simpler functions now fit onto just a single line, and it doesn’t even inconvenience me to see them this way: I know the codebase well enough by now that it’s no disadvantage for me to edit it in this condensed format.

Screenshot of a block of Javascript code intended using semicolons rather than tabs or spaces.
Personally, I’ve given up on the tabs-vs-spaces debate and now I indent my code using semicolons. (That’s clearly a joke. Don’t flame me.)

In the next version, I shorten the names of variables and functions in the code.

For some reason, the original developer used epic rambling strings for function names, like the well-known function dedicateIslandTempleToTheImageOfAGodBeforeOrAfterMakingASacrificeWithOrWithoutDancing( boolBeforeMakingASacrifice, objectImageOfGodToDedicateIslandTempleTo, stringNmeOfPersonMakingDedication, stringOrNullNameOfLocalIslanderDancedWith). That one gets called all the time internally and isn’t exposed via the external API so it might as well be shortened to d=(i,j,k,l,m)=>. Now all the internal workings of the library are each represented with just one or two letters.

v1.1.2 changes

  • Shortened/standarised non-API variable and function names – improves performance

I’ve shaved several kilobytes off the monstrous size of TheseusJS and I’m very proud. The original developer says nice things about my fork on social media, resulting in a torrent of downloads and attention. Within a certain archipelago of developers, I’m slightly famous.

But did I violate the license?

But then a developer says to me: you’re violating the license of the original project because you’re not making the source code available!

A man in a suit sits outdoors with a laptop and a cup of coffee. He is angry and frustrated, and a bubble shows that he is thinking:"why can't people respect the fucking license?!"
This happens every day. Probably not to this same guy every time though, but you never know. Original photo by Andrea Piacquadio.

They claim that my bugfix in the first version of FastTheseusJS represents a material change to the software, and that the changes I’ve made since then are obfuscation: efforts short of binary compilation that aim to reduce the accessibility of the source code. This fails to meet the GPL‘s definition of source code as “the preferred form of the work for making modifications to it”. I counter that this condensed view of the source code is my “preferred” way of working with it, and moreover that my output is not the result of some build step that makes the code harder to read, the code is just hard to read as a result of the optimisations I’ve made. In ambiguous cases, whose “preference” wins?

Did I violate the license? My gut feeling is that no, all of my changes were within the spirit and the letter of the GPL (they’re a terrible way to write code, but that’s not what’s in question here). Because I manually condensed the code, did so with the intention that this condensing was a feature, and continue to work directly with the code after condensing it because I prefer it that way… that feels like it’s “okay”.

But if I’d just run the code through a minification tool, my opinion changes. Suppose I’d run minify --output fasttheseus.js theseus.js and then deleted my copy of theseus.js. Then, making changes to fasttheseus.js and redistributing it feels like a violation to me… even if the resulting code is the same as I’d have gotten via the “manual” method!

I don’t know the answer (IANAL), but I’ll tell you this: I feel hypocritical for saying one piece of code would not violate the license but another identical piece of code would, based only on the process the developer followed to produce it. If I replace one piece of code at a time with less-readable versions the license remains intact, but if I replace them all at once it doesn’t? That doesn’t feel concrete nor satisfying.

Screenshot showing highly-minified HTML code (for this page) which is still reasonably readable.
Sure, I can write a blog post in just one line of code. It’ll just be a really, really, really long line… (Still perfectly readable, though!)

This isn’t an entirely contrived example

This example might seem highly contrived, and that’s because it is. But the grey area between the extremes is where the real questions are. If you agree that redistribution of (only) minified source code violates the GPL, you’re left asking: at what point does the change occur? Code isn’t necessarily minified or not-minified: there are many intermediate steps.

If I use a correcting linter to standardise indentation and whitespace – switching multiple spaces for the appropriate number of tabs, removing excess line breaks etc. (or do the same tasks manually) I’m sure you’d agree that’s fine. If I have it replace whole-function if-blocks with hoisted return statements, that’s probably fine too. If I replace if blocks with ternery operators or remove or shorten comments… that might be fine, but probably depends upon context. At some point though, some way along the process, minification goes “too far” and feels like it’s no longer within the limitations of the license. And I can’t tell you where that point is!

This issue’s even more-complicated with some other licenses, e.g. the AGPL, which extends the requirement to share source code to hosted applications. Suppose I implement a web application that uses an AGPL-licensed library. The person who redistributed it to me only gave me the minified version, but they gave me a web address from which to acquire the full source code, so they’re in the clear. I need to make a small patch to the library to support my service, so I edit it right into the minified version I’ve already got. A user of my hosted application asks for a copy of the source code, so I provide it, including the edited minified library… am I violating the license for not providing the full, unminified version, even though I’ve never even seen it? It seems absurd to say that I would be, but it could still be argued to be the case.

Diagram showing how permissive software licenses are generally compatible for use in LGPL or MPL licensed software, which are then compatible for use (except MPL) in GPL licensed software, which are in turn compatible for use (except GPL 2) with AGPL licensed software.
I love diagrams like this, which show license compatibility of different open source licenses. Adapted from a diagram by Carlo Daffara, in turn adapted from a diagram by David E. Wheeler, used under a CC-BY-SA license.

99% of the time, though, the answer’s clear, and the ambiguities shown above shouldn’t stop anybody from choosing to open-source their work under GPL, AGPL (or any other open source license depending on their preference and their community). Perhaps the question of whether minification violates the letter of a copyleft license is one of those Potter Stewart “I know it when I see it” things. It certainly goes against the spirit of the thing to do so deliberately or unnecessarily, though, and perhaps it’s that softer, more-altruistic goal we should be aiming for.

Standing up for developers: youtube-dl is back

This article is a repost promoting content originally published elsewhere. See more things Dan's reposted.

Today we reinstated youtube-dl, a popular project on GitHub, after we received additional information about the project that enabled us to reverse a Digital Millennium Copyright Act (DMCA) takedown.

This is a Big Deal. For two reasons:

Firstly, youtube-dl is a spectacularly useful project. I’ve used it for many years to help me archive my own content, to improve my access to content that’s freely available on the platform, and to help centralise (freely available) metadata to keep my subscriptions on video-sharing sites. Others have even more-important uses for the tool. I love youtube-dl, and I’d never considered the possibility that it could be used to circumvent digital restrictions (apparently it’s got some kind of geofence-evading features you can optionally enable, for people who don’t have a multi-endpoint VPN I guess?… I note that it definitely doesn’t break DRM…) until its GitHub repo got taken down the other week.

Which was a bleeding stupid thing to use a DMCA request on, because, y’know: Barbara Streisand Effect. Lampshading that a free, open-source tool could be used for people’s convenience is likely to increase awareness and adoption, not decrease it! Huge thanks to the EFF for stepping up and telling GitHub that they’d got it wrong (this letter is great reading, by the way).

But secondly, GitHub’s response is admirable and – assuming their honour their new stance – effective. They acknowledge their mistake, then go on to set out a new process by which they’ll review takedown requests. That new process includes technical and legal review, erring on the side of the developer rather than the claimant (i.e. “innocent until proven guilty”), multiparty negotiation, and limiting the scope of takedowns by allowing violators to export their non-infringing content after the fact.

I was concerned that the youtube-dl takedown might create a FOSS “chilling effect” on GitHub. It still might: in the light of it, I for one have started backing up my repositories and those of projects I care about to an different Git server! But with this response, I’d still be confident hosting the main copy of an open-source project on GitHub, even if that project was one which was at risk of being mistaken for copyright violation.

Note that the original claim came not from Google/YouTube as you might have expected (if you’ve just tuned in) but from the RIAA, based on the fact that youtube-dl could be used to download copyrighted music videos for enjoyment offline. If you’re reminded of Sony v. Universal City Studios (1984) – the case behind the “Betamax standard” – you’re not alone.

When One Library Steals From Another

When I first started working at the Bodleian Libraries in 2011, their websites were looking… a little dated. I’d soon spend some time working with a vendor (whose premises mysteriously caught fire while I was there, freeing me up to spend my birthday in a bar) to develop a fresh, modern interface for our websites that, while not the be-all and end-all, was a huge leap forwards and has served us well for the last five years or so.

The Bodleian Libraries website as it appeared in 2011.
The colour scheme, the layout, the fact that it didn’t remotely work on mobiles… there was a lot wrong with the old design of the Bodleian Libraries’ websites.

Fast-forward a little: in about 2015 we noticed a few strange anomalies in our Google Analytics data. For some reason, web addresses were appearing that didn’t exist anywhere on our site! Most of these resulted from web visitors in Turkey, so we figured that some Turkish website had probably accidentally put our Google Analytics user ID number into their code rather than their own. We filtered out the erroneous data – there wasn’t much of it; the other website was clearly significantly less-popular than ours – and carried on. Sometimes we’d speculate about the identity of the other site, but mostly we didn’t even think about it.

Bodleian Library & Radcliffe Camera website
How a Bodleian Libraries’ website might appear today. Pay attention, now: there’ll be a spot-the-difference competition in a moment.

Earlier this year, there was a spike in the volume of the traffic we were having to filter-out, so I took the time to investigate more-thoroughly. I determined that the offending website belonged to the Library of Bilkent University, Turkey. I figured that some junior web developer there must have copy-pasted the Bodleian’s Google Analytics code and forgotten to change the user ID, so I went to the website to take a look… but I was in for an even bigger surprise.

Bilkent University Library website, as it appears today.
Hey, that looks… basically identical!

Whoah! The web design of a British university was completely ripped-off by a Turkish university! Mouth agape at the audacity, I clicked my way through several of their pages to try to understand what had happened. It seemed inconceivable that it could be a coincidence, but perhaps it was supposed to be more of an homage than a copy-paste job? Or perhaps they were ripped-off by an unscrupulous web designer? Or maybe it was somebody on the “inside”, like our vendor, acting unethically by re-selling the same custom design? I didn’t believe it could be any of those things, but I had to be sure. So I started digging…

Bodleian and Bilkent search boxes, side-by-side.
Our user research did indicate that putting the site and catalogue search tools like this was smart. Maybe they did the same research?


Bodleian and Bilkent menus side-by-side.
Menus are pretty common on many websites. They probably just had a similar idea.


Bodleian and Bilkent opening hours, side-by-side.
Tabs are a great way to show opening hours. Everybody knows that. And this is obviously just the a popular font.


Bodleian and Bilkent sliders, side-by-side.
Oh, you’ve got a slider too. With circles? And you’ve got an identical Javascript bug? Okay… now that’s a bit of a coincidence…


Bodleian and Bilkent content boxes, side-by-side.
Okay, I’m getting a mite suspicious now. Surely we didn’t independently come up with this particular bit of design?


Bodleian and Bilkent footers, side-by-side.
Well these are clearly different. Ours has a copyright notice, for example…


Copyright notice on Bilkent University Library's website.
Oh, you DO have a copyright notice. Hang on, wait: you’ve not only stolen our design but you’ve declared it to be open-source???

I was almost flattered as I played this spot-the-difference competition, until I saw the copyright notice: stealing our design was galling enough, but then relicensing it in such a way that they specifically encourage others to steal it too was another step entirely. Remember that we’re talking about an academic library, here: if anybody ought to have a handle on copyright law then it’s a library!

I took a dive into the source code to see if this really was, as it appeared to be, a copy-paste-and-change-the-name job (rather than “merely” a rip-off of the entire graphic design), and, sure enough…

HTML source code from Bilkent University Library.
In their HTML source code, you can see both the Bodleian’s Google Analytics code (which they failed to remove) but also their own. And a data- attribute related to a project I wrote and that means nothing to their site.

It looks like they’d just mirrored the site and done a search-and-replace for “Bodleian”, replacing it with “Bilkent”. Even the code’s spelling errors, comments, and indentation were intact. The CSS was especially telling (as well as being chock-full of redundant code relating to things that appear on our website but not on theirs)…

CSS code from Bilkent University.
The search-replace resulted in some icky grammar, like “the Bilkent” appearing in their code. And what’s this? That’s MY NAME in the middle of their source code!

So I reached out to them with a tweet:

Tweet: Hey @KutphaneBilkent (Bilkent University Library): couldn't help but notice your website looks suspiciously like those of @bodleianlibs...?
My first tweet to Bilkent University Library contained a “spot the difference” competition.

I didn’t get any response, although I did attract a handful of Turkish followers on Twitter. Later, they changed their Twitter handle and I thought I’d take advantage of the then-new capability for longer tweets to have another go at getting their attention:

Tweet: I see you've changed your Twitter handle, @librarybilkent! Your site still looks like you've #stolen the #webdesign from @bodleianlibs, though (and changed the license to a #CreativeCommons one, although the fact you forgot to change the #GoogleAnalytics ID is a giveaway...).
This time, I was a little less-sarcastic and a little more-aggressive. Turns out that’s all that was needed.

Clearly this was what it took to make the difference. I received an email from the personal email account of somebody claiming to be Taner Korkmaz, Systems Librarian with Bilkent’s Technical Services team. He wrote (emphasis mine):

Dear Mr. Dan Q,

My name is Taner Korkmaz and I am the systems librarian at Bilkent. I am writing on behalf of Bilkent University Library, regarding your share about Bilkent on your Twitter account.

Firstly, I would like to explain that there is no any relation between your tweet and our library Twitter handle change. The librarian who is Twitter admin at Bilkent did not notice your first tweet. Another librarian took this job and decided to change the twitter handle because of the Turkish letters, abbreviations, English name requirement etc. The first name was @KutphaneBilkent (kutuphane means library in Turkish) which is not clear and not easy to understand. Now, it is @LibraryBilkent.

About 4 years ago, we decided to change our library website, (and therefore) we reviewed the appearance and utility of the web pages.

We appreciated the simplicity and clarity of the user interface of University of Oxford Bodlien Library & Radcliffe Camera, as an academic pioneer in many fields. As a not profit institution, we took advantage of your template by using CSS and HTML, and added our own original content.

We thought it would not create a problem the idea of using CSS codes since on the web page there isn’t any license notice or any restriction related to the content of the template, and since the licenses on the web pages are mainly more about content rather than templates.

The Library has its own Google Analytics and Search Console accounts and the related integrations for the web site statistical data tracking. We would like to point out that there is a misunderstanding regarding this issue.

In 2017, we started to work on creating a new web page and we will renew our current web page very soon.

Thank you in advance for your attention to this matter and apologies for possible inconveniences.

Yours sincerely,

Or to put it another way: they decided that our copyright notice only applied to our content and not our design and took a copy of the latter.

Do you remember when I pointed out earlier that librarians should be expected to know their way around copyright law? Sigh.

They’ve now started removing evidence of their copy-pasting such as the duplicate Google Analytics code fragment and the references to LibraryData, but you can still find the unmodified code via, if you like.

That probably ends my part in this little adventure, but I’ve passed everything on to the University of Oxford’s legal team in case any of them have anything to say about it. And now I’ve got a new story to tell where web developers get together over a pint: the story of the time that I made a website for a university… and a different university stole it!