A metronome that increases/decreases tempo automatically. Stable tempo as usual is also supported of course.

AxlMetronome

BandLab

beat-tap

A personal music player/streamer. You need to install a piece of software on your PC / NAS called node-mp3stream (source: https://github.com/lucienimmink/node-mp3stream, installation using docker/Synology NAS: https://www.arielext.org/syno-docker.html). Once you are it installed and added a new user you can connect to is using JSMusicDB. JSMusicDB is written using web technology and distributed as PWA. At just over 60KB this app is packed with features like:
- multiple themes
- optimized album-art display
- spectrum analyser
- fuzzy search
- playlist management/generation
- last.fm integration
- and much more

JSMusicDB

Lil Beat Maker

Imagine being able to simply type out playlists on a blank sheet and listen to them —no logins, no interruptions, free... 
that is exactly what Lineamp allows you to do.

On Lineamp you have the greatest music database in existence. Build your playlist with songs, podcasts, live shows, audio books, lyrics and more. Then save your playlists, share them, view popular lists and so much more.

Lineamp

MusicKit

Song Search

Star Track is a simple way to save your favorite songs for later lookup.

Star Track

Free online instrument tuner. Tune your guitar, ukulele, violin or any other instrument.
Get in tune easily and accurately without installing anything.