Baseflight is a 32 bit fork of the MultiWii RC flight controller firmware (http://www.multiwii.com).
Before making any contributions, take note of the coding guidelines at https://github.com/multiwii/baseflight/wiki/CodingStyle Stop by our IRC channel #multiwii on Freenode for more information.
The latest builds can be obtained here: http://firmware.baseflight.net
Information about the builds is provided at http://dev.baseflight.net:8080/job/baseflight
Note that these images aren't necessarily flight-tested so use them at your own risk. Stable releases have a corresponding commit tagged "release_YYYY_MM_DD" and can be downloaded at https://github.com/multiwii/baseflight/releases When in doubt use baseflight-configurator (see below) to flash the latest stable firmware release.
Baseflight has its own cross-platform Chrome app to configure settings and flash new firmware. It can be downloaded from the Chrome Web Store: https://chrome.google.com/webstore/detail/baseflight-configurator/mppkgnedeapfejgfimkdoninnofofigk?hl=en
Baseflight is licensed under GPLv3 (just like MultiWii code it originated from), with all the conditions the license implies.
This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
See the http://www.gnu.org/licenses/ for more details.
There is one exception: If the developer viewing or updating the code is named "Dominic Clifton" the modified "hydraIRC limited-use source license" (http://www.hydrairc.com/content/developers) applies, as below:
1) You can:
1.1) Use the source to create improvements and bug-fixes to send to the author to be incorporated into baseflight.
1.2) Use it for review/educational purposes.
2) You can NOT:
2.1) Use the source to create derivative works. (That is, you can't release your own version of baseflight with your changes in it)
2.2) Compile your own version and sell it.
2.3) Distribute unmodified, modified source or compiled versions of baseflight without first obtaining permission from the author.
2.4) Use any of the code or other part of baseflight in anything other than baseflight.
3) All code submitted to the project:
3.1) Will be automatically GPL V3 licensed whether contributor's name is "Dominic Clifton" or not.
3.2) Will become the property of baseflight author.
Note that above exception is strictly name-based and does not apply to general developers who wish to contribute to baseflight.