Open in Browser for Slack

A Chrome extension that opens Slack message links (https://xxx.slack.com/archives/...) in the Slack web client in your browser, instead of launching the Slack desktop app, and highlights the linked message. It also works on Chromium-based browsers such as Dia.

This is an unofficial extension and is not affiliated with, endorsed by, or sponsored by Slack Technologies, LLC or Salesforce, Inc.

Install from the Chrome Web Store

Background

Slack currently handles message links with the following flow:

1. xxx.slack.com/archives/... → Slack shows a "Launching <workspace>" interstitial (data-qa="ssb_redirect_loading_page") on the workspace domain itself and fires a slack:// deep link to launch the desktop app.
2. That interstitial offers an "open this link in your browser" escape link, which carries a skip_today query param. Clicking it opens the message in app.slack.com/client/... and tells Slack to skip the interstitial for the rest of the day.

Existing similar extensions (e.g. "Open Slack in Browser, not App") inject their content script into *.slack.com/archives/* but look for a link on app.slack.com, so they never run against the interstitial as it is actually rendered today. This extension injects into https://*.slack.com/archives/* — the message-link paths where the interstitial actually renders. That covers every workspace subdomain (e.g. uzabase.slack.com) without also running the redirect script on the heavy web client (app.slack.com/client) or on service subdomains such as files.slack.com and api.slack.com. (The separate highlight script described below is the one exception: it runs on app.slack.com/client/* and exits immediately when the URL carries no message timestamp.)

How it works

The extension watches for the "open this link in your browser" link with a MutationObserver (and also checks once on load, since the interstitial is server-rendered and the link may already be present) and clicks it as soon as it appears.

The link has no stable data-qa of its own, so it is matched by its skip_today query param, scoped to the interstitial container ([data-qa="ssb_redirect_loading_page"]) so a stray link elsewhere in the web client is never clicked.

Clicking the link (rather than navigating to its href) lets Slack persist the "open in browser today" state (skip_today), so subsequent links on the same day open directly in the browser without the interstitial.

Highlighting the target message

After the redirect lands on the web client (app.slack.com/client/...), Slack scrolls to the target message but gives little visual indication of which one it is. A second content script (highlight.js + highlight.css) fixes this:

1. At document_start — before the SPA boots and rewrites the URL — it extracts the target message timestamp from the path (/p<10 digits><6 digits>, or a bare <10>.<6> segment).
2. It watches the DOM for the message node carrying that timestamp (data-item-key / id, matched by suffix since thread panes prefix the value with the channel id).
3. Once the node renders, it applies a translucent yellow highlight that holds for a few seconds and fades out. Until the fade completes, a node that loses the highlight (the virtual list recycling the row, or Slack rewriting the row's classes) is re-tagged with a resume offset so the fade continues where it left off instead of restarting.

Installation

From the Chrome Web Store (recommended)

Install from the Chrome Web Store page.

From source (development)

1. Open the extension management page
   • Chrome: chrome://extensions
   • Dia: open Extensions from the menu (equivalent to chrome://extensions)
2. Enable "Developer mode"
3. Click "Load unpacked" and select this folder

If you install both, disable one of them — two copies would race to click the same link.

After editing the extension (or pulling an update), click the reload icon on its card so the new manifest.json, content scripts, and CSS take effect.

If the "Open Slack in Browser, not App" extension is installed, disable it. It never runs on the current message-link flow, but it still injects into other *.slack.com/archives/* pages, where it can navigate away or show its failure alert unexpectedly.

Verifying it works

While Slack's skip_today state is active (after choosing "use browser" once that day), the interstitial itself is not shown and links open directly in the browser. To verify the auto-click, test after the state expires — e.g. on the first link click the next day. If the interstitial flashes briefly and you are then taken to the message automatically, it is working.

Limitations

• Depending on the timing of the slack:// deep link versus the auto-click, the OS-level "Open Slack.app?" dialog may still appear (the browser navigation itself completes behind the dialog)
• If Slack changes the interstitial DOM (the container data-qa or the skip_today param), the selector will need to be updated
• The extension watches for the link for 15 seconds per page load; if the interstitial renders later than that (e.g. on a very slow connection), it is not clicked
• The highlight relies on the web client exposing the message timestamp in data-item-key / id and on the URL still containing the timestamp at document_start; if Slack changes either, the highlight silently does nothing (the redirect itself is unaffected)
• The highlight only runs on a fresh page load of app.slack.com/client/... (the redirect case); clicking a message link while the web client is already open navigates in-SPA and is not highlighted