Contributing to the ViennaRNA Package


General Remarks

The ViennaRNA Package is developed by humans and consequently may contain bugs that prevent proper operation of the implemented algorithms. If you think you have found any of those nasty animals, please help us to improve our software by reporting the bug to us.

The ViennaRNA Package also is open-source software, which means that everybody can have a closer look into our implementations to understand and potentially extend it’s functionality. If you implemented any novel feature into the ViennaRNA Package that might be of interest to a larger community, please don’t hesitate to ask for merging of your code into our official source tree. See the Pull Request Process section below to find information on how to do that.

Please note that we have a code of conduct. Please follow it in all your interactions with this project.

If you wish to contribute to this project, please first discuss any proposed changes with the owners and main developers. You may do that either through making an issue at our official GitHub presence, by email, or any other personal communication with the core developer team.

More importantly, if you wish to contribute any files or software, you need to agree to our ViennaRNA Package Contributors License Agreement (CLA)! Otherwise, your contributions can’t be merged into our source tree. See below for further information and the full CLA details.

Reporting Bugs

  1. Please make an issue at GitHub or notify us by emailing to

  2. In your report, include as much information as possible, such that we are able to reproduce it. If possible, find a minimal example that triggers the bug.

  3. Include the version number for the ViennaRNA Package you experience the bug with.

  4. Include at least some minimal information regarding your operating system (Linux, Mac OS X, Windows, etc.)

Pull Request Process

  1. Ensure that you have not checked-in any files that are automatically build!

  2. When contributing C source code, follow our code formatting guide lines. You may use the tool uncrustify together with our config located in misc/uncrustify.cfg to accomplish that.

  3. Only expose symbols (functions, variables, etc.) to the libraries interface that are absolutely necessary! Hide all other symbols in the corresponding object file(s) by declaring them as static.

  4. Use the prefixes vrna_ for any symbol you add to the API of our library! Preprocessor macros in header files require the prefix in capital letters, i.e. VRNA_.

  5. Use C-style comments at any place necessary to make sure your implementation can still be understood and followed in the future.

  6. Add test cases for any new implementation! The test suite is located in the tests directory and is split into tests for the C-library, executable programs, and the individual scripting language interfaces.

  7. Run make check to ensure that all other test suites still run properly with your applied changes!

  8. When contributing via GitHub, make a personal fork of our project and create a separate branch for your changes. Then make a pull request to our user-contrib branch. Pull requests to the master branch will be rejected to keep its history clean.

  9. Pull requests that have been successfully merged into the user-contrib branch usually find their way into the next release of the ViennaRNA Package. However, please note that the core developers may decide to include your changes in a later version.

Contributors License Agreement

Thank you for your interest in contributing to the ViennaRNA Package (“We” or “Us”).

Before contributing, please note that we adopted a standard Contributors License Agreement (CLA) agreement provided by Project Harmony, a community-centered group focused on contributor agreements for free and open source software (FOSS).

This contributor agreement (“Agreement”) documents the rights granted by contributors to Us. To make this document effective, please sign it and send it to Us by email to

The respective CLA PDF documents are available in the doc/CLA directory of the distribution tarball, and online at our official ViennaRNA Website.