Chrome extension

Slowed Reverb Chrome Extension

The slowed reverb Chrome extension for YouTube explained: what it does, install steps, permissions, version history, Firefox alternative and honest limits.

Slow & Reverb for YouTube is a free Chrome extension that applies a slowed + reverb effect to whatever is playing on YouTube or YouTube Music, live, in the tab. It is the companion to the web editor on this site, built by the same people, with the same controls, but for a different job. The editor turns your files into MP3s. The extension turns your listening into a slowed session and leaves no file behind.

This page is the listing written out in plain language: what the extension does, how to install it, what the two permissions mean, where to find the version history, what to use on Firefox, and the limits we would rather you knew before installing. For specific uses, see slow down YouTube videos, YouTube reverb and YouTube Music.

What it is

The extension is independent and is not affiliated with or endorsed by YouTube or Google.

What it does

When you open a YouTube or YouTube Music page, the extension attaches to the player and routes its audio through a processing chain built on the Web Audio API. You control that chain from a popup in the toolbar.

Speed sets the playback rate. By default pitch follows speed, so slowing to 0.85x also drops the key by roughly three semitones, which is the classic slowed sound. Reverb is the wet mix of a convolution reverb, and Space is its decay time. Bass and Tone are low and high shelves for weight and darkness. Width adjusts the stereo image. The built-in presets give you a deep slowed sound, a lighter one, and a dry reset, and you can save your own.

Because the extension changes the player's playback rate, the picture slows with the sound and stays in sync. Because it processes the audio on the way to your speakers, the video on YouTube is untouched and nobody else hears your settings. The effect follows playlists, autoplay and the YouTube Music queue, and your settings persist between videos and sessions.

Install

1. Visit the Chrome Web Store listing.
2. Click Add to Chrome and accept the permission prompt.
3. Reload any YouTube tab that was already open.
4. Pin the icon from the extensions menu so the popup is one click away.

Edge, Brave and other Chromium browsers install from the same listing. Edge may show a banner about allowing extensions from other stores; accept it.

To update, Chrome handles it automatically. To check your version, open chrome://extensions, find Slow & Reverb for YouTube and read the version line.

Permissions, in one paragraph each

tabs. The extension needs to know which tab is a YouTube or YouTube Music tab so it can attach its controls to the right player and so the popup reflects the state of the tab you are looking at. It does not read page content on other sites and does not collect browsing history.

storage. Your current settings and any custom presets are saved in Chrome's extension storage so they are still there on the next video and after a restart. The data stays on your machine. There is no account and no sync to our servers.

That is the full list. There is no host permission for other websites, no access to downloads, no microphone and no identity. The extension permissions page covers how to review and revoke these in Chrome if you want to see them for yourself.

Version history

The current version is 0.2.1. Earlier releases established the core speed and reverb chain on YouTube and then extended it to YouTube Music and added preset saving. The full list of changes, with dates and what each version fixed, lives on the changelog, which is shared between the extension and the web editor. If something changed in the extension that you did not expect, that page is the first place to look.

Firefox alternative

Slow & Reverb for YouTube is built on Chrome's extension APIs and is not published for Firefox. If you use Firefox, a separate add-on called Slowverb exists for the same purpose, applying slowed and reverb to YouTube playback. It is not made by us, so its controls and behaviour differ, but the idea is the same. Safari has no equivalent we can point to.

Honest limitations

Most extension listings read like adverts. This one would rather you knew the edges.

• Desktop only. Mobile Chrome, Android and iOS do not run extensions. On a phone, use the web editor with your own files.
• YouTube domains only. YouTube embeds on other websites, desktop app wrappers, and video cast to a TV are not processed.
• No export of any kind. The extension does not download, record or save audio. That is by design and will not change. If you need a file, use the editor with audio you own.
• One setting for everything. Speed and reverb apply to whatever is playing. A long mixed playlist will have songs that want a different speed; you adjust or skip.
• Ads come through slowed. The extension cannot distinguish an ad from the video in the same player.
• CPU cost. Convolution reverb is real processing. On an old machine with many media tabs you may hear dropouts. Lowering Reverb helps.
• Extreme speeds sound extreme. Below about 0.70x vocals smear on any tool. The slider goes there, but 0.80x to 0.90x is where songs live.
• No stem separation, no chopping, no independent pitch shift. Pitch follows speed unless preserved, same as the editor.

How it relates to the web editor

The extension and the editor share a processing philosophy and the same control names, so a preset you like in one translates to the other. They do different jobs. The extension is for listening to music you do not own on a platform you do not control, and it respects that by never making a copy. The editor is for your own files and gives you an MP3 at 96 kbps, 32 kHz, encoded in your browser, suitable for YouTube, TikTok and Shorts. The extension versus web editor page lays the two out side by side.

Open the free editor: upload MP3, WAV, AAC, OGG or FLAC, adjust speed, reverb, bass, tone, width and space, then export MP3 or a ZIP of many tracks. Everything runs in your browser.