This repo contains a Scripkit widget that provides lyrics for the currently playing spotify track. The most cool thing right now is the possibility to have the sing-along feature exactly as if you are inside of the official Spotify client.
All the lyrics are fetched from the Musixmatch API made available by Spotify after their partnership.
N.B: Almost surely this is a violation of Spotify Terms of Service so I discourage you to use this tool, it was mainly developed for learning purposes only.
My main purpose was to learn something new as always.
Anyway it's also useful to me because while I work I really enjoying having this window on another screen and sing along the track I'm currently playing in my headphones.
About authentication
The main behind authentication was to get the accessToken making a HTTP request to https://open.spotify.com using the local Chrome cookies and extrapolate the accessToken property from the script tag with id session.
This flow works but right now is ony available and working in the fetch-token.js file because the implementation with Scripkit is still giving me troubles with sqlite (at least on my Mac with m1).
Once that I'll solve this problem the authentication will be smoother and definitely more effective than now.
So How can I authenticate the widget right now ?
First thing first you have to authenticate yourself on Chrome going on https://open.spotify.com.
Once you authenticated you can simply execute the fetch-token.js script and it will log you your token, necessary for making API calls.
About Musixmatch lyrics service
Spotify right now expose an API endpoint to fetch all the lyrics of the given track, also with timing for each row and with colors.
The exposed API is the following: https://spclient.wg.spotify.com/color-lyrics/v2/track/<spotify-track-id>
If you call this api providing the accessToken and the spotify-track-id you will receive the lyrics, if available, along with colors and timings.
Jacopo De Gattis