Contributing means helping out.

When you contribute anything to the project—code, documentation, bug fixes, suggestions or just good advice—we assume you do this with permission and you are not breaking any contracts or laws by providing that to us. If you do not have permission, do not contribute it to us.

Contributing to a project like curl could be many different things. While source code is the stuff that is needed to build the products, we are also depending on good documentation, testing (both test code and test infrastructure), web content, user support and more.

Send your changes or suggestions to the team and by working together we can fix problems, improve functionality, clarify documentation, add features or make anything else you help out with land in the proper place. We make sure improved code and docs get merged into the source tree properly and other sorts of contributions are suitable received.

Send your contributions on a mailing list, file an issue or submit a pull request.


Ideas are easy, implementations are hard. Yes, we do appreciate good ideas and suggestions of what to do and how to do it, but the chances that the ideas actually turn into real features grow substantially if you also volunteer to participate in converting the idea into reality.

We already gather ideas in the TODO document and we are generally aware of the current trends in the popular networking protocols so there is usually no need to remind us about those.

What to add

The best approach to add anything to curl or libcurl is, of course, to first bring the idea and suggestion to the curl project team members and then discuss with them if the idea is feasible for inclusion and then how an implementation is best done—and done in the best possible way to get merged into the source code repository, assuming that is what you want.

The project generally approves functions that improve the support for the current protocols, especially features that popular clients or browsers have but that curl still lacks.

Of course, you can also add contents to the project that are not code, like documentation, graphics or website contents, but the general rules apply equally to that.

If you are fixing a problem you have or a problem that others are reporting, we are thrilled to receive your fixes and merge them as soon as possible,

What not to add

There are no good rules that say what features you can or cannot add or that we never accept, but let me instead try to mention a few things you should avoid to get less friction and to be successful, faster:

  • Do not write up a huge patch first and then send it to the list for discussion. Always start out by discussing on the list, and send your initial review requests early to get feedback on your design and approach. It saves you from wasting time going down a route that might need rewriting in the end anyway.

  • When introducing things in the code, you need to follow the style and architecture that already exists. When you add code to the ordinary transfer code path, it must, for example, work asynchronously in a non-blocking manner. We do not accept new code that introduces blocking behaviors—we already have too many of those that we have not managed to remove yet.

  • Quick hacks or dirty solutions that have a high risk of not working on platforms you do not run or on architectures you do not know. We do not care if you are in a hurry or that it works for you. We do not accept high risk code or code that is hard to read or understand.

  • Code that breaks the build. Sure, we accept that we sometimes have to add code to certain areas that makes the new functionality perhaps depend on a specific 3rd party library or a specific operating system and similar, but we can never do that at the expense of all other systems. We do not break the build, and we make sure all tests keep running successfully.


Our preferred source control tool is git.

While git is sometimes not the easiest tool to learn and master, all the basic steps a casual developer and contributor needs to know are straight-forward and do not take much time or effort to learn.

This book does not help you learn git. All software developers in this day and age should learn git anyway.

The curl git tree can be browsed with a web browser on our GitHub page at

To check out the curl source code from git, you can clone it like this:

git clone

Pull request

A popular and convenient way to make your own changes and contribute them back to the project is by doing a so-called pull request on GitHub.

First, you create your own version of the source tree, called a fork, on the Github website. That way you get your own version of the curl git tree that you can clone to a local copy.

You edit your own local copy, commit the changes, push them to the git repository on Github and then on the Github website you can select to create a pull request based on your changes done to your local repository clone of the original curl repository.

We recommend doing your work meant for a pull request in a dedicated separate branch and not in master, just to make it easier for you to update a pull request, like after review, for example, or if you realize it was a dead end and you decide to just throw it away.

Make a patch for the mailing list

Even if you opt to not make a pull request but prefer the old fashioned and trusted method of sending a patch to the curl-library mailing list, it is still a good practice to work in a local git branch and commit your changes there.

A branch makes it easy to edit and rebase when you need to change things and it makes it easy to keep syncing to the master branch when things are updated upstream.

Once your commits are fine enough to get sent to the mailing list, you just create patches with git format-patch and send them away. Even more fancy users go directly to git send-email and have git send the email itself.

git commit style

When you commit a patch to git, you give it a commit message that describes the change you are committing. We have a certain style in the project that we ask you to use:

[area]: [short line describing the main effect]

[separate the above single line from the rest with an empty line]

[full description, no wider than 72 columns that describes as much as
possible as to why this change is made, and possibly what things
it fixes and everything else that is related]

[Bug: link to source of the report or more related discussion]
[Reported-by: John Doe—credit the reporter]
[whatever-else-by: credit all helpers, finders, doers]

Do not forget to use git commit --author="Jane Doe <>" if you commit someone else's work, and make sure that you have your own Github username and email setup correctly in git before you commit via commands below:

git config --global "johndoe"
git config --global ""

The author and the *-by: lines are, of course, there to make sure we give the proper credit in the project. We do not want to take someone else's work without clearly attributing where it comes from. Giving correct credit is of utmost importance.

Who decides what goes in?

First, it might not be obvious to everyone but there is, of course, only a limited set of people that can actually merge commits into the actual official git repository. Let's call them the core team.

Everyone else can fork off their own curl repository to which they can commit and push changes and host them online and build their own curl versions from and so on, but in order to get changes into the official repository they need to be pushed by a trusted person.

The core team is a small set of curl developers who have been around for several years and have shown they are skilled developers and that they fully comprehend the values and the style of development we do in this project. They are some of the people listed in the The development team section.

You can always bring a discussion to the mailing list and argue why you think your changes should get accepted, or perhaps even object to other changes that are getting in and so forth. You can even suggest yourself or someone else to be given "push rights" and become one of the selected few in that team.

Daniel remains the project leader and while it is rarely needed, he has the final say in debates that do not seem to sway in either direction or fail to reach consensus.