Let's get the honest part out of the way first, because most pages about "Slack skins" bury it: Slack does not have skins. Not in the sense you probably mean — no full-app reskin, no downloadable packs that restyle the message area, no custom fonts, no alternate layouts. If you arrived here hoping to make Slack look like Discord, Winamp, or a terminal, the official answer is no.
What Slack does let you change is a smaller, specific list: the sidebar colors, light or dark mode, the workspace icon and name, custom emoji, and a handful of display preferences. Stack all of those together and a workspace can look and feel distinctly yours — which is the closest thing to a Slack skin that exists. This guide walks through every one of those levers, gives you copy-paste theme strings, and finishes with the unofficial browser-extension route and why we'd think twice before using it.
What a "Slack Skin" Actually Covers
Here's the whole surface area, so you know what you're working with before you start clicking through preferences.
| Element | Can you change it? | Who sees it |
|---|---|---|
| Sidebar colors (eight positions) | Yes — built-in themes or a custom hex string | Only you |
| Light / dark / system mode | Yes | Only you |
| Message area background | Light or dark only — no colors, no images | Only you |
| Font family | No | — |
| Font size / zoom, compact vs. clean layout | Yes | Only you |
| Workspace icon and name | Yes (admins) | Everyone |
| Custom emoji | Yes (anyone, unless admins restrict it) | Everyone |
| Mobile app theme | Light / dark / system; custom strings ignored | Only you |
Notice the split in that last column. Sidebar themes and dark mode are personal settings — your coworkers never see them. The workspace icon and custom emoji are shared — they're the only "skin" elements that change Slack for the whole team. Keep that distinction in mind when someone asks you to "theme the workspace."
Step 1: Reskin the Sidebar with a Theme
The sidebar is where nearly all of Slack's visual personality lives, and it's the one place you get real color control. Open Preferences (Cmd+, on Mac, Ctrl+, on Windows) → Appearance. You'll see Slack's bundled themes first — Aubergine, Clementine, Banana, and friends — and below them a Custom theme section where you can paste a string of eight hex colors.
Three to start with, straight from our full collection of Slack themes:
Midnight Teal (dark)
#0B2B33,#0E3A45,#167891,#FFFFFF,#11515F,#D8ECF1,#8BD6D4,#FF5FA2
Paper & Ink (light)
#F8F8F6,#EDEDEA,#2B6CB0,#FFFFFF,#E8E8E4,#3D4852,#38A169,#D53F8C
Confetti Pop (loud)
#167891,#12657F,#FF5FA2,#FFFFFF,#11515F,#E9F7F6,#8BD6D4,#FF5FA2
The eight values control, in order: column background, hover menu background, active item, active item text, hover item, text color, active presence dot, and mention badge. Slack previews every edit live, so the fastest way to build your own is to paste the closest match and change one position at a time. Themes are saved per workspace, which is the real trick — give each of your workspaces its own palette and you'll stop posting in the wrong #general.
Step 2: Pick a Color Mode (and Let the OS Decide)
In the same Appearance pane, choose Light, Dark, or Sync with OS setting. This is the only control over the message area's background — it flips between white and near-black and that's it. Pair dark sidebar themes with dark mode, or the sidebar and message pane will fight each other.
"Sync with OS" is the underrated option: if your Mac or Windows machine shifts to dark at sunset, Slack follows along without you touching anything.
Step 3: Adjust the Layout, Density, and Size
Not skins exactly, but these settings change how the message area feels more than anything else you can toggle:
- Preferences → Messages & media → Theme: Clean shows avatars and spacing; Compact strips it down to name-and-text lines, IRC-style. Heavy Slack users often prefer Compact for the sheer information density.
- Preferences → Accessibility → Zoom (or
Cmd +/Cmd -): the only way to change text size. There's no font-size setting separate from this. - Names: show full names, display names, or both — same Messages & media pane.
- Preferences → Accessibility: underline links, stop emoji from animating, and reduce motion if you find the default UI twitchy.
If you're already in preferences, learning a few keyboard shortcuts pays off far more than any visual tweak — a fast Slack feels nicer than a pretty one.
Step 4: Change the Workspace Icon and Name (Admins)
This is the one shared branding element, and it's worth doing properly because it shows up in the workspace switcher, notifications, and every invite email. Workspace owners and admins: click the workspace name → Tools & settings → Workspace settings, then the Workspace icon tab. Upload a square image — at least 132×132 pixels, but 512×512 or larger looks crisp everywhere Slack shrinks it. The workspace name and URL live under the Settings tab in the same admin area.
Keep it bold and simple — it renders at roughly favicon size in the sidebar rail, and logos with fine text turn into smudges.
Step 5: Build a Custom Emoji Pack
If the sidebar theme is the wallpaper, custom emoji are the furniture — and they're the most visible way to make a Slack workspace feel like it belongs to your team. Click the workspace name → Tools & settings → Customize workspace, then Add custom emoji. Images need to be square, ideally 128×128, and under 128KB; GIFs work, and animated ones are the surest route to becoming a workspace legend.
A few ideas that reliably earn their keep: your company logo, every teammate's face (with consent), the product mascot, and a small set of reaction emoji that mean something specific — :shipped:, :looking:, :nice-catch:. That last kind is more than decoration. Emoji reactions are the lightest form of recognition that exists, and teams that build a vocabulary of them tend to be teams that notice each other's work. If you want to go further than a reaction, a dedicated recognition channel turns that instinct into a habit.
Admins can restrict emoji uploads to admins only under Workspace settings → Permissions, but in our experience the open setting produces a better culture and, occasionally, a better pack.
Step 6: Mobile Appearance
The mobile apps support far less. On iOS and Android, go to You → Preferences → Appearance and you can choose light, dark, or follow the system. That's the extent of it — custom sidebar theme strings from desktop are ignored on mobile, so your phone stays close to stock no matter how elaborate your laptop looks. Your custom emoji and workspace icon, being shared workspace elements, do show up everywhere.
The Unofficial Route: Extensions and CSS Injection
Because Slack in the browser is a web page, you can restyle it with a user-styles extension (Stylus is the usual choice) that injects your own CSS — full message-area backgrounds, custom fonts, hidden UI elements, the works. There are also purpose-built "Slack theme" browser extensions. And for the desktop app, which is an Electron wrapper, people have historically patched the app's bundled files to inject CSS; the pre-2019 "black theme" scripts that predated official dark mode worked exactly this way.
We're not going to tell you not to. We are going to list the caveats, because they're substantial:
- It's unsupported. Slack doesn't document its class names or DOM structure, and it ships updates constantly. Custom CSS breaks without warning — sometimes weekly.
- Browser only, in practice. Extensions can't touch the desktop app. Patching the desktop app's files breaks its code signature, which on macOS can disable auto-updates or refuse to launch, and reverts on the next update anyway.
- Security. An extension that can restyle Slack can read everything in it — every message, every DM, every file name. Only install one whose source you can inspect, and never one from an unknown publisher. If your company runs managed devices, this may also violate policy outright.
- Nobody else sees it. Like every personal setting, it changes your view only.
Our take: a Stylus rule you wrote yourself for the browser is a reasonable hobby. A random "Slack skins" extension from the Chrome store is not worth the risk for a different message background.
Quick Answers
Can you change the Slack background?
Only between light and dark mode. There is no setting for a custom color or image behind the message area. The sidebar is the only region with full color control, via the theme string described above.
Can you change the Slack font?
No. Slack once had a hidden /slackfont command that let you swap the typeface; it was removed years ago. Today you can change size (zoom) and density (Clean vs. Compact), but not the font family — short of the CSS-injection route and its caveats.
Can you theme the workspace for the whole team?
Partly. The workspace icon, name, and custom emoji are shared, and they're the elements that actually brand a workspace. Sidebar themes and color mode are strictly personal and can't be enforced by admins. The practical workaround: pin your team's theme string in a welcome channel and mention it in onboarding — most people paste it within a day. If you're setting a workspace up from scratch, our Slack getting-started guide covers what to decide before the first invite goes out.
Skins Are the Easy Part
Twenty minutes with the steps above gets you as far as Slack's customization goes: a sidebar in your colors, a proper icon, an emoji pack with inside jokes in it. It's worth doing. But a reskinned Slack is still just a place where messages happen — what makes a workspace feel good to open in the morning is what shows up in it. Propsly (yes, it's ours) adds a peer recognition feed to Slack: anyone types /props to celebrate a teammate, and every give lands publicly in a channel of your choosing. Free for unlimited users, 200 props per person per month. Pick a theme first, though. It's the fun part.