utubmp3 adds a ⬇ MP3 button next to Like and Share on YouTube. Click it, and a few seconds later the song is in your Downloads folder as a properly tagged MP3 with its cover art. Install the app, open it once, turn on the extension, and that’s the whole setup. No Terminal, Homebrew, or Python.

Download for macOS Download for Windows (beta) Free · open source (MIT) · macOS 13+ (Apple Silicon & Intel, notarized by Apple) · Windows 10/11 with Chrome or Edge

What it does

One-click MP3: a button sits right in YouTube’s action bar (it floats in the corner on Shorts). It turns into ⏳ while converting and ✅ Saved when done; click it to show the file in Finder.
Tags that are actually right: every download is tagged with the title, singers, album or movie, composer, lyricist, and label, parsed from the video description. Hashtags, social links, and the pasted-in description are stripped out, and the file is renamed to Title - Album.mp3.
A tag editor in the toolbar: the popup lists your recent MP3s with Clean and Edit buttons. Edit any tag, or clear a field to remove it. Audio and cover art are never re-encoded.
Keeps working when YouTube changes: the downloader updates itself daily, and if a download fails it updates and retries once on the spot.
Runs on your computer: nothing leaves your machine except the download from YouTube. No account, no analytics, no servers.

Install

Mac

Download the DMG, drag utubmp3 to Applications, and open it once.
Click Quit and Open Safari Settings… and turn on the extension. Allow it on youtube.com when Safari asks.
Open any YouTube video and click ⬇ MP3.

Using Chrome on a Mac? Install and open the Mac app first (it runs the downloads), then download the Chrome extension, unzip it, open chrome://extensions, turn on Developer mode, and click Load unpacked. Google’s Web Store doesn’t allow YouTube downloaders, so this is the only way to install it in Chrome.

Windows (beta)

Run utubmp3-setup.exe. It installs for your user only, with no admin prompt. It isn’t code-signed yet, so if SmartScreen says “Windows protected your PC”, click More info → Run anyway.
On the last page, leave Open the extension folder ticked.
In chrome://extensions (or edge://extensions), turn on Developer mode, click Load unpacked, and pick that folder.
Open any YouTube video and click ⬇ MP3.

How it works

Browser extensions aren’t allowed to run programs, so utubmp3 runs a small background helper: on a Mac it’s the app’s own executable, started at login by launchd; on Windows it’s utubmp3.exe, started at sign-in. The extension talks to it over a local connection, and the helper does the heavy lifting with yt-dlp and ffmpeg.

YouTube page → Safari / Chrome extension → helper (127.0.0.1) → yt-dlp + ffmpeg → ~/Downloads

The helper only listens on 127.0.0.1, refuses requests from web pages (and DNS-rebinding tricks), only accepts YouTube video links, and only touches .mp3 files directly in Downloads.
ffmpeg and the QuickJS runtime are bundled and signed; yt-dlp is downloaded on first run so it can update itself, since YouTube regularly breaks old versions.
The app is signed with a Developer ID and notarized by Apple, and runs outside the App Store because a sandboxed app can’t start the helper.
On Windows the helper is a Go port of the Swift one, with the same API and checks, so the same extension talks to either. The installer is per-user and adds an uninstaller to Settings → Apps.
ffmpeg is a minimal build compiled from source with only the audio and tagging parts utubmp3 uses: about 7 MB on the Mac and 3 MB on Windows, instead of a 160 MB full build.

Why I built it

Online converter sites are full of pop-ups and hand back files with junk names and no tags. utubmp3 does the same job from a button on the video itself, runs entirely on the Mac, and hands back a file that’s named and tagged the way a music app expects.

Only download content you have the rights to, such as your own uploads or openly licensed videos. Downloading from YouTube may be against its Terms of Service.