An open source fork of RhodeCode called Kallithea was recently released. I've added it to the list but with criticisms since it is new (far riskier to use than anything else on this list).
I added a new project I found, srchub. However, since it doesn't change my final recommendation of SCM-Manager, I kept it in this same answer.
First note, I assume by:
Operating systems: Must run under Windows and at least one of [Linux, OSX].
you mean that it can be installed on either a Windows based server and either a Linux or OSX based server.
I too ran into the same problem (and disappointment) with RhodeCode switching to a very confusing, non-open source license. So I dug up my old research list on potential self-hosted Mercurial web apps and tried to update it. This is what I came up with:
Open Source (free)
- This is an open source fork of RhodeCode starting from the last version before it went business source (so 1.7.2).
- It supports Mercurial and Git.
- The license is now GPLv3.
- It obviously has all the features of RhodeCode seeing as it is a fork of the project.
- Criticisms - Being new (July 2014), there are many things to worry about:
- There is no guarantee that this project will remain active in the long term.
- Their website is sparse with info, and they don't directly mention that they are a fork of RhodeCode which makes me feel a bit wary of their honestly (especially since they have a donate button).
- Their only documentation is a rebrand of what RhodeCode's was. So it does not appear that they've added any new features. I would hope that they've fixed a bunch of bugs at least.
- They don't have a clear roadmap, just a list of things they plan to do. That is never a good sign for project longevity.
- Not all is bad though as they are backed by the Software Freedom Conservancy, Inc. so there is some legitimacy to the project. I urge anyone considering this to read their blog post here about the project.
- Java based so can be deployed on all OSes.
- Supports Git, Mercurial and Subversion over HTTP.
- Open Source (BSD License).
- It focuses on repository and user management, but you can get features such as issue tracking, graphs, etc. via plugins.
- Although the instructions are Linux-only, I believe it can be installed on Windows Servers since the minimum requirements are Apache 2, PHP 5 and PostgreSQL 8.x.
- It supports GNU arch, Bazaar, CVS, Darcs, Git, Mercurial, and Subversion.
- It is an open source (GNU GPL2+) fork of GForge before that project went closed source.
- I haven't looked into this one much, but it should have a lot of features like other "forges" (ex: see Allura which I list later on).
- Build on PHP so it should be able to be deployed on all OSes.
- Supports Git, Mercurial, Subversion, and Monotone.
- Open Source (GNU GPL License).
- It is a clone of Google Code so that should give you an idea of the other features it has.
- The lead dev & his company backing it used to have a paid hosting option for those who didn't want to run it on their own servers. However, it got end-of-lifed back in 2012 (shutdown date in 2013) so it doesn't seem to be actively developed anymore.
- This is a fork (appears to have started around Aug 2013) of the abandoned Indefero project above, so the feature set should be identical.
- Looking at the recent commit log, they do appear to be attempting to maintain the old project. I do see a few issues fixed but as it appears to be a one man show, it does not seem to be moving very quickly.
- This one is cheating a bit per your Windows + Linux or OSX req, but since one of the methods for installation is to use Vagrant and run it in a virtual machine, you can technically the server on Windows.
- Supports Git, Mercurial, and Subversion.
- This is the software the runs SourceForge, so I think that is the best summary of its feature list.
- Version 3 requires PHP, Perl, Apache, and MySQL so it should run on any OS.
- Open Source (GNU GPL v2+).
- There is also a PHP5 rewrite and Django rewrite. Neither of which I believe were completed.
- Supports CVS, GNU arch, Subversion, Git, Mercurial, and Bazaar.
- I believe this project is abandoned as I think it was merged with FusionForge (above). So not going to go into other features.
I found none that fulfilled your two requirements. Not that there were many to look through.
- It can only be installed on Windows Servers, so it fails your first requirement.
- Their pricing is straightforward though (only service I found with clear pricing).
- It fails your pricing requirement as they do the "ask for quote" thing too.
And that's it aside from RhodeCode.
For completeness sake, if you want to look into other open source projects that don't meet your Windows + Linux/OSX requirement or are simply dead, there are:
- Note, as far as I can tell, this project is not very actively maintained.
- Since the site doesn't seem to even exist anymore, I assume the project is dead.
In my opinion, SCM-Manager is your best bet in terms of ease of setup if all you need is repository and user management (and if the plugins suffice for your other needs). All of the other options either:
- Require a lot of system resources to run,
- are more difficult to setup,
- or are not as actively developed (if at all).
Kallithea, being an open source fork is clearly an alternative. But I stand by my criticisms since I've seen many old projects (such as some on this list) die after not gaining community traction post fork+rebranding. Unless you are ok with possibly going a migration again, I would not suggest using this until a lot of time has passed.
Lastly, if you want to look into non-self-hosted options, you can see the Mercurial Project's own list here: Mercurial Hosting