mal-decimal-scores is a Google Chrome extension that allows you to give decimal scores for your anime on MyAnimeList.
When enabled, the normal 1-10 system is replaced with one from 1.0 to 10.0. Rounded integer scores are saved on MyAnimeList as usual, and decimal scores are saved using Chrome sync so that they are available on any device you have using Chrome.
Currently, the extension is not available in packaged form. This may change in the future.
To install it from source, first clone the repository into a permanent location. Then, go to chrome://extensions, enable the "Developer mode" checkbox in the top right corner, click on "Load unpackaged extension...", and choose the directory of the git repository.
You will need to pack the extension yourself if you want scores to be synced
between multiple computers. Click on the "Pack extension..." button and choose
the git repository directory as the extension root. After the extension is
packed, open the resulting
.crx file in all copies of Chrome that you want to
share the same set of scores.
Usage should be mostly straightforward – in any place where you would previously rate an anime by selecting a score from a dropdown menu, you can now enter a number. Decimal scores are enabled on your list page, individual anime pages, pages where you can add to/edit your list, and the "shared anime" page.
Scores can be exported by going to the standard list
export page, which will cause a
animelist_decimal_scores.json file to be downloaded to your computer. Scores
can be loaded from this file by going to the
Only anime can be given decimal scores. Manga scores are not affected.
As noted above, only you can see your decimal scores. Others will see your scores rounded to integer values.
Due to data restrictions in Chrome sync, there is an upper limit to the number of anime you can give a decimal score. This limit should be no less than a few thousand titles. You can check your data usage by going to the export page.