There are lots of reasons why Drupal was forked to create Backdrop. Of those, these are the most notable:
Technical Difference
Starting with version 8, Drupal took a very different turn from Drupal 7 and previous versions. Though many of the features in Drupal 8 are very similar to those in Drupal 7, the code underneath bears very little resemblance to the Drupal of the past.
We see value in maintaining the code that has a proven track record of success. Is it perfect the way it was? Of course not, that's why this is a fork, and not long-term-support. Backdrop CMS already includes many modernizations, and will continue adding new features every 4 months.
Target Audience
Backdrop best serves organizations that need the complex and feature-rich functionality of Drupal 7, but without the expensive upkeep required of modern Drupal.
Backdrop CMS is specifically intended for use by non-profit organizations, educational institutions, and small to medium sized businesses. This doesn't mean that Backdrop won't also be a great product for others, but as Backdrop changes and improves, features intended for this audience will be prioritized.
Diverging priorities
The most important issues for the Backdrop community are not necessarily the most important issues for the Drupal community, and vice versa. When the priorities diverge, so will the code.
Example: Headless CMS
The Drupal community agreed that Drupal core should have a built-in solution for operating Drupal with a separate front-end site. For Backdrop, you can run your site that way if you want to, but it's not enough of a priority for our audience that supporting tools would be moved into core.
Example: Configuration management
Though both Drupal and Backdrop CMS have configuration management as a feature, they are implemented differently for each project. Backdrop chose to store its configuration in JSON files and without a required database cache, because an on-disk JSON solution was more in line with the following 2 principles: Simplicity, and Speed & performance.
See our principles for a more detailed explanation of what Backdrop stands for.
Decision Making
How did Drupal 8 end up so different from Drupal 7? It might have to do with the organic decision making process used by the Drupal community. If we disagree with the outcome of the that process, the only way to prevent the same thing from happening to our project is to adopt a different process.
There are a lot of fantastic features in Drupal that were added because one organization needed that feature, and was willing to contribute the hours necessary to get it in. In the end, many of these features ended up being used by less than 1% of sites running on Drupal.
The Backdrop Project Management Committee can oversee new features being added to core, and ensure that they benefit most of the Backdrop community. Fantastic ideas that do not make the 80% mark, will be left to contrib.
Read more about our leadership structure.
