This is a prototype I built with Vue.js for aligning japanese audio and text using the Needleman–Wunsch algorithm on katakana. For converting japanese kanji to katakana I also created a web build of mecab in another repository: mecab-web-worker
The result is hosted with GitHub Pages: https://leyhline.github.io/ja-align/
Here's also a small video for a short introduction, although I wouldn't recommand watching because I had a slight cold when I did the recording (and because of my accent, obviously).