Earlier this week, my favorite citation management tool Mendeley announced that it had sold itself to a very large, for-profit scholarly publishing company, Elsevier. There have been mixed reactions to this.

Mendeley is useful to academics and researchers on several fronts. The desktop application helps folks organize all the PDFs of journal articles that live on their computer. It is kind of like an iTunes for journal article PDFs, helping users create folders, rename files and automatically download the metadata (author, title, journal, etc.) that comes with the articles. Mendeley helps users collaborate with others by sharing reading lists and files and helping folks discover new research based on their interests. And Mendeley helps users create in-text citations and works cited sections in their manuscripts.

All of that tends to fit with what Elsevier does: publishing scholarly journals and databases.

But there are some real differences in the reputations of the two companies, and some real differences in how the two companies have approached the various "open" movements related to academic publishing (open access, open science, open data etc.). Some of these differences can be seen in Jason Hoyt's (now of PeerJ, formerly of Mendeley) reaction to the news.

Mendeley has appeared to embrace "openness" in several ways. It uses a "freemium" model, where the basic product is free and users can pay for additional storage space or more collaboration features. Mendeley embraced alternative metrics, a hallmark of open access publications like PLOS ONE. Mendeley released an incredibly useful Open API that has allowed a lot of really creative people to create a lot of really creative tools. Although they don't publish anything themselves, they have associated themselves with open access to scholarly research.

Elsevier, on the other hand, has not embraced "openness" in any meaningful way. They charge a lot of money for their products, leading some researchers to boycott the company. They have been reluctant to automatically grant researchers the right to use text mining techniques with their products, even when researchers have already paid for access to those journals via library subscriptions. And they appear to have an overall corporate philosophy that goes against the principles of openness. A 2012 report aimed at Elsevier stockholders (and potential stockholders) suggested that the company has an "obsession with maintaining a huge degree of control on both content and its access" and suggested that this wasn't a good long-term strategy: "We continue to be baffled by Elsevier's perception that controlling everything (for example by severely restricting text- and data mining applications) is essential to protect its economics."

So this acquisition of Mendeley by Elsevier has some folks shaking their head. Some folks are feeling betrayed, vowing to discontinue using the product. Despite reassurances, some users are concerned that Mendeley will cease to be available for free. Others feel this sale (for about $70-$100 million, according to TechCrunch) is a vote of confidence demonstrating just how good Mendeley is.

The companies are trying to mitigate concerns. They started by giving things away: every Mendeley user will now see their online storage capacity doubled (from 1GB to 2GB for users at the free level). In the Q and A posted on their website, Mendeley seeks to reassure users that nothing bad will happen. The problem is that the power relationship has changed. As Mike Taylor points out, Mendeley is no longer in charge and would have to abide by decisions made by Elsevier.

Admittedly, the sale makes me rethink my views on Mendeley as a company. I recently reviewed their related product, Mendeley Institutional Edition (MIE), for Library Journal, and my colleagues and I spoke with a representative about it just yesterday. MIE is interesting but expensive, and as we talked, the representative discussed their flexible pricing options. Will this flexibility remain now that they are owned by Elsevier (who is not known for flexible pricing models)? My library already sends a lot of money in Elsevier's direction for journals and databases, and I'll admit I'm reluctant to send any more their way.

It will take some time to see how this all plays out: there are philosophical issues as well as user experience issues to look at. William Gunn, Mendeley liaison to the academic community, suggests that this represents an honest move by Elsevier to rehabilitate the reputation I've described above, and the official Elsevier announcement of the acquisition suggests this a bit.

In the meantime, I will continue to use Mendeley and recommend it to those I work with. But I'll be paying close attention to policy changes and updates, and I'll be backing up my data.