Chrome Side Panel Image Compressor: Compress Photos While You Work

Photo Compressor is a Chrome extension that opens an image compressor in the browser’s side panel, so JPEG, PNG, WEBP and GIF files get compressed right on top of the tab you’re already working in, without switching windows or losing your place. It’s a genuine picture compressor built for Chrome, not a generic web tool wrapped in a tab — the whole point is that it never needs to take over the screen.

Install from the Chrome Web Store — the extension is free, and the side panel opens the moment the icon is pinned.

What the Chrome side panel is and why a picture compressor belongs there

Chrome’s side panel is a first-class part of the browser, not a makeshift window — it opens along the right edge of the page and stays there while the page underneath keeps working. Extensions got access to it through the chrome.sidePanel API starting in Chrome 114, and it only runs on Manifest V3, with a "sidePanel" permission declared in the manifest. According to Chrome’s own developer documentation, a panel can be scoped to a whole browser window or pinned to one specific tab.

The side panel is a first-class Chrome surface, not a popup

A regular extension popup closes the instant you click anywhere outside it — click past the queue of images to check something on the page, and the queue is gone. The side panel is built to behave differently: Chrome’s documentation on creating a side panel describes it as staying open across tab switches when configured that way. In practice that means a popup-based tool forces you to compress images one at a time, restarting the flow after every accidental click, while a panel lets you move between tabs and keep adding files to the same list.

Which extensions actually use it

The side panel isn’t exclusive to Photo Compressor, but it’s rare. Image Resizer Extension also runs in a side panel, though it resizes rather than compresses and caps free use at five operations before asking for payment. ShrinkSuite is a WebAssembly project distributed from GitHub with no Chrome Web Store listing at all. Compress Image and the two extensions both named Image Compressor still run as ordinary popups. Most “best extensions for compressing images” roundups don’t mention the side panel as a category, because so few tools use it.

Opening the panel and pinning the icon

Getting the panel open takes one extra step the first time, and none after that.

Install, then pin

Add the extension from the Chrome Web Store, click the puzzle-piece icon to the right of the address bar, and pin Photo Compressor so its icon stays visible on the toolbar. The extension’s own manifest labels that toolbar button “Click to open panel” — there’s no separate menu to dig through.

One click opens the workspace

Clicking the pinned icon opens the panel immediately. Chrome only added the ability for an extension to open its panel programmatically — sidePanel.open() — in Chrome 116, and per the API reference that call requires a user gesture: a click on the icon, a keyboard shortcut, or a context-menu action. The panel can’t pop open on its own while you’re reading something else.

Three ways to get pictures into the panel

There isn’t one required workflow — the panel accepts images from wherever you happen to have them.

• The ADD IMAGES button — a standard file picker that lets you select several images from disk at once.
• Drag and drop straight onto the panel — pull files from a folder or the desktop directly into the open panel, and it accepts the whole batch in one drop.
• Right-click any image on any page — the fastest of the three, and the only one covered in the section below because it doesn’t require downloading anything first.

Right-clicking an image anywhere on the web brings up Compress Image in the context menu, and the compressed result lands straight in the panel — no save-to-disk step in between.

Full click-by-click instructions for each method live on the how-to page.

Downloads: where the compressed files land

Once images are compressed, the panel gives two ways to get them out.

1. Click the download icon on an individual thumbnail to save just that one file.
2. Or click DOWNLOAD ALL once the whole queue is ready, and every compressed image comes down together in one ZIP archive.
3. Rename the output before downloading if you want a specific file name instead of the source name.
4. Use CLEAN ALL to clear the panel’s queue once you’re done — this only empties the list, it doesn’t touch files already saved to disk.

For a batch of five files that’s a minor convenience; for fifty, DOWNLOAD ALL is the difference between one click and fifty. Setting your own output file name also avoids Chrome auto-appending (1), (2) to duplicate names in the downloads folder — a small thing, but Compressor.io actually charges for custom renaming, while it’s included here. Everything a batch run can do is covered in more depth on the features page.

Files always land in Chrome’s regular downloads folder — there’s no separate storage the extension keeps for itself, so nothing has to be moved or exported afterward.

Real workflows the panel was built for

The panel’s real advantage shows up less in any single feature and more in how it fits around other tabs — this is what separates a proper photo compressor built into the browser from a tool that only lives in its own tab.

Filling in a form with a hard size limit. A government portal or bank form caps photo uploads at 200 KB, and the form is already open in the next tab. Compress the image down to that size in the panel and attach it immediately, without leaving the page or losing anything already typed into the form.

Email attachments. Mail providers cap attachment size — Gmail allows up to 25 MB per message — and a handful of phone photos can easily exceed that on their own. Compressing them by the usual 50-70% brings a batch back under the limit without individually resizing each one.

Pictures for a CMS or an online store. Product photos, post covers, gallery images — the panel sits open next to the admin screen, so the loop becomes compress, insert, move to the next item.

Avatars and profile pictures. Many services reject an avatar for its file size rather than its dimensions. Right-click the image already on screen, and it’s ready to upload seconds later.

Screenshots for a bug tracker. A screenshot attached to a Jira ticket or GitHub issue needs to stay readable without ballooning to several megabytes. The panel stays open next to the tracker for as long as it takes to write up the report.

Everything is computed locally

Compression runs entirely inside the browser, on the machine it’s installed on — images are never uploaded to a server, so the compression step itself works without an internet connection at all, even mid-flight on a plane. The extension asks for activeTab, storage, sidePanel and contextMenus permissions, plus the site access needed to add the right-click menu item to images on any page. As stated on its Chrome Web Store listing, the developer does not collect or use user data. Chrome’s own guidance on extension permissions explains why a compressor needs activeTab and site access in the first place — read more on the access page.

Users should be able to review permissions to understand what data an extension can access, and developers should request only the narrowest permissions needed for their extension to function.

Chrome for Developers — Declare permissions

Formats, ratios and honest numbers

Photo Compressor handles JPEG, PNG, WEBP and GIF. Compression typically runs 50-70%, and on individual files it can reach as high as 90% depending on the source. Real results captured from the panel: 157.6 KB down to 56.0 KB, 290.2 KB down to 80.7 KB, and 348 KB down to 150.3 KB. Across one batch of five photos the panel’s own savings badges read -61%, -64%, -66%, -61% and -72%. This is lossy compression, not a lossless trick: the software is tuned so the difference doesn’t read to the eye at normal settings, but it isn’t “zero quality loss” in the literal sense. Step-by-step walkthroughs of every setting live on the documentation page.

Official sources

• chrome.sidePanel API — developer.chrome.com/docs/extensions/reference/api/sidePanel
• Create a side panel — developer.chrome.com/docs/extensions/develop/ui/create-a-side-panel
• Chrome extensions documentation — developer.chrome.com/docs/extensions
• Photo Compressor in the Chrome Web Store — chromewebstore.google.com/detail/photo-compressor

FAQ

Install from the Chrome Web Store and try the side panel on the next image you need to shrink. For a closer look at what the extension can do beyond the panel, see features, how to use it, permissions and access, the full documentation, or head back to the image compressor in Chrome home page.