One of the most common mistakes learners make is confusing a kanji with another that looks similar. While WaniKani does offer a “Visually Similar Kanji” feature, it’s not always available—and even when it is, it doesn’t always include the kanji you actually mistook it for.
A valuable improvement would be the ability to manually add the kanji you confused it with during lessons or reviews. This would allow learners to directly compare the two side by side and better understand their differences.
For example, during a recent review, I mistook 負 for 角. To me, they look quite similar, but WaniKani didn’t list them as visually similar. If I could add 角 as a custom visually similar kanji for 負, I’d be able to compare them directly and reinforce the distinction in my memory.
Adding a feature to let users create their own list of visually similar kanji would make the learning process more personalized and effective.