Group Tabs by Collection

A Zotero plugin that groups open reader/snapshot tabs by collection, with collapsible group chips — similar to Chrome's tab groups.

I decided to implement this after realizing this was a common complaint about Zotero, and a long-standing feature request. If Zotero releases an official feature, this plugin should probably not be used.

What it does

When you have many PDFs or snapshots open at once, the Zotero tab bar becomes a flat, unorganised list. This plugin lets you group those tabs by the Zotero collection each item belongs to:

• A coloured group chip appears before each collection's first tab, labelled with the collection name.
• Click a chip to collapse the group — the tabs fold away and the chip shows a count badge. Click again to expand.
• Right-click a chip for a context menu with "Close all tabs in …".
• Right-click a tab for a "Move to group" submenu to reassign it to any existing group, or "Remove from group" to ungroup it entirely.
• Drag a tab onto a group chip to move it into that group.
• Manual assignments (via right-click or drag) persist — they survive the button being clicked again and Zotero restarts.
• Right-click items in the item list for an "Open in tab group(s)" option that opens and groups them in one step.
• When there are multiple groups, all start collapsed so you get an instant overview. When everything belongs to one collection the group starts expanded (collapsing it would leave nothing visible).
• Opening a PDF from a collection that already has a group automatically slots it in — the group chip and tint appear without any action needed.
• Up to 8 distinct colours are assigned automatically (blue, green, orange, purple, teal, rose, amber, indigo).
• Tabs within a group are tinted with that group's colour.
• Items with no collection are placed at the end, ungrouped.
• Group state is restored automatically after a Zotero restart — groups, colours, collapsed state, and manual assignments all come back within a couple of seconds of opening Zotero.

Usage

1. Select papers in the item list and right-click → "Open in tab group(s)" to open and group them in one step, or open PDFs/snapshots manually and then click the four-box button in the tab bar (or Tools → Group Tabs by Collection).
2. Tabs are reordered and coloured group chips appear in the tab bar.
3. Click a chip to collapse or expand that group; right-click for close-all.
4. Any PDF you open from a grouped collection is automatically slotted in — no need to click the button again.

The four-box button: first run vs. subsequent runs

First run (no groups exist yet): all open reader tabs are sorted by collection, chips are created, and tabs are physically reordered in the tab bar.

Subsequent runs (groups already exist): the button only processes tabs that are not yet assigned to any group. Already-grouped tabs — including any you have manually moved — are left exactly where they are. If an ungrouped tab belongs to a collection that already has a group, it is added to that group. If it belongs to a new collection, a new group is created for it. This means you can open a handful of new papers, click the button once, and only those new papers are slotted in, without disturbing anything else.

If a tab's item belongs to multiple collections, behaviour depends on how it was opened:

• Via the button: a confirmation dialog lists each conflict and suggests placing the tab under the first matching collection alphabetically. You can proceed or cancel.
• Via auto-assign (tab opened directly from the library while groups are active): the tab is silently placed into the first group whose collection name matches, with no prompt.
• On restart restore: conflicts are resolved silently using the same alphabetical default.

Installation

Download the latest group-tabs-by-collection.xpi from the Releases page.

In Zotero: Tools → Add-ons → gear icon → Install Add-on From File…

Requires Zotero 7, 8, 9, or 10.

Building from source

macOS / Linux

git clone https://github.com/ppavlidis/group-tabs-by-collection.git
cd group-tabs-by-collection
bash build-xpi.sh

Windows (PowerShell, no WSL required)

git clone https://github.com/ppavlidis/group-tabs-by-collection.git
cd group-tabs-by-collection
Compress-Archive -Path manifest.json,bootstrap.js,group-tabs.js,style.css,updates.json,content -DestinationPath group-tabs-by-collection.zip -Force
Rename-Item group-tabs-by-collection.zip group-tabs-by-collection.xpi

Then install the resulting group-tabs-by-collection.xpi as above.

Releasing

.github/workflows/build.yml builds the XPI on every push and attaches it to the GitHub release when a v* tag is pushed. Bump version in manifest.json and add a matching entry to updates.json (with its update_link and an applications.zotero block) — the workflow refuses a tag whose version, manifest and update manifest disagree, and checks the built archive for the files it must contain. Zotero reads updates.json from main to offer in-app updates.

git tag vX.Y.Z && git push origin vX.Y.Z

Notes

• Restart behaviour: group state is saved to Zotero's preferences store whenever it changes, and restored automatically on the next startup. Your tabs reopen as normal (Zotero's own behaviour), and within a couple of seconds the plugin re-applies groups, colours, collapsed state, and any manual assignments. No action required.
• If a group cannot be restored — for example because all its tabs were closed before the restart — it is silently dropped.
• Multi-collection conflicts that arise on restore are resolved automatically using the same first-alphabetically default as the manual dialog; no prompt is shown.