Slack's built-in dark mode darkens the message pane and then hands you a sidebar in one of a handful of stock palettes. If you want the sidebar to go properly black, or charcoal, or deep plum, you need a custom theme string. This is a gallery of the best Slack dark themes we could build and live with: fifteen new palettes, from pure-black OLED themes to warm near-blacks with a single accent, each as a copy-paste string with a note on how readable it actually is after a long day.
None of these repeat the dark themes in our main gallery of the best Slack themes or the editor ports in our Nord, Dracula, and Catppuccin themes for developers. This is the second helping.
How to Apply a Slack Dark Theme String
Open Slack, press Ctrl+, (or Cmd+,), go to Appearance, expand Custom theme, and paste. It applies live, with no save button. Or post the string in any channel or DM and click the Switch sidebar theme button Slack attaches under it. The full walkthrough, including the browser-versus-desktop quirks, is in how to change your Slack theme.
Every string below is eight six-digit hex colors in Slack's fixed order: column background, hover menu background, active item, active item text, hover item, text color, active presence, mention badge. If you want to tweak one, our decoder for Slack theme colors explains what each slot does. Themes are personal and per-workspace, so nobody else sees yours.
True Black vs. Dark Grey: Which Slack Dark Theme to Choose
Two schools of dark, and they feel different on different screens.
| True black (#000000) | Dark grey (#1A1A1A to #2E2E2E) | |
|---|---|---|
| On OLED | Black pixels switch off: infinite contrast, a little less battery drain | Looks like a normal dark app |
| On LCD | Backlight shows through as a faint grey anyway | Same, so nothing lost |
| Eye strain | Bright text on pure black can "halo" for some people, especially in a dark room | Gentler; the step from text to background is smaller |
| Next to dark mode | Sidebar is visibly darker than the message pane | Blends in with the message pane |
The practical rule: on an OLED laptop with a taste for hard edges, go true black and keep the text light grey rather than pure white. On an LCD, or if white-on-black text swims for you, pick a dark grey. Every theme below lists its text-to-background contrast ratio; anything above 7:1 is comfortable for small channel names, and all fifteen clear it.
True Black and OLED Slack Themes
Void
#000000,#0D0D0D,#167891,#FFFFFF,#161616,#B3B3B3,#8BD6D4,#FF5FA2
Pure black with a deep teal active channel and a pink badge. The only color on screen is the channel you're in. Text is a soft grey at 10:1, chosen so it doesn't glow.
Obsidian Ember
#000000,#111111,#F97316,#000000,#1A1A1A,#C4C4C4,#4ADE80,#FACC15
Black with a hot orange active bar and a gold mention badge. The warmest of the OLED set. Text runs at 12:1; the orange bar uses black text inside it, which stays crisp at 7.5:1.
Pitch Violet
#000000,#120A1F,#A78BFA,#0B0614,#1C1128,#C9C2DB,#34D399,#FB7185
Black background, but every surface around it (hover, menu, text) carries a violet tint, so the whole sidebar reads purple without a single purple panel. Lavender active bar with near-black text; 12:1 on the channel names.
Carbon Fiber
#050505,#141414,#38BDF8,#061018,#1E1E1E,#9CA3AF,#22C55E,#F43F5E
Almost-black with sky-blue highlights and the most muted text in this post, a cool grey at 8:1. Looks like a hardware spec sheet. If channel names feel faint, swap the text slot for #B9C0C9.
Dark Grey and Charcoal Slack Themes
Slate Night
#1E293B,#273449,#38BDF8,#0F172A,#334155,#CBD5E1,#4ADE80,#FB7185
Blue-leaning slate, the dark grey most modern web apps use. Sky-blue active channel with navy text, coral badge. Text at just under 10:1; the closest match here to Slack's own dark-mode message pane.
Ash
#2B2B2B,#363636,#D4D4D4,#1A1A1A,#404040,#BDBDBD,#7CC57A,#FF6B6B
Fully monochrome: grey background, light-grey active bar with dark text, grey hover states. The only color is the green presence dot and a red badge. Softest contrast here at 7.5:1, which is the point; nothing on it shouts.
Smoke & Brass
#26231F,#2F2B26,#C9A227,#1C1915,#3A3530,#DCD3C3,#9ACD7A,#F06A6A
Warm charcoal with a brushed-brass active channel and parchment-colored text. Reads like an old library lamp. Text at 10.5:1; the brass bar carries dark text inside it at 7:1.
Steel Blue
#1B2430,#232E3C,#6FA8DC,#0F1620,#2C394A,#C7D0DB,#5FD39B,#F77F7F
A cooler charcoal than Slate Night, with a dusty steel-blue active bar instead of a bright one. The low-key option for a work Slack where the sidebar shouldn't have a personality. Text at 10:1.
Deep Color Slack Dark Themes
These are dark first and colored second: the background is a saturated hue pushed almost to black, so the sidebar has a mood without the glare of a bright one.
Abyssal Blue
#06283D,#0A3652,#1FA6C8,#06283D,#0E4466,#CFE3EE,#5BE3B8,#FF7A59
Deep-sea navy with a bright cyan active channel and a seaglass presence dot. The coral badge is the only warm thing in it, so mentions pop. Text at 11.5:1; the cyan bar uses navy text, which is more legible than white would be on that shade.
Charcoal Rose
#1F1A1C,#2A2326,#E8688A,#1F1A1C,#342B2F,#E3D6DA,#8BD6D4,#FFB4C6
Charcoal with a faint pink warmth, a rose active bar, and a pale-pink badge. Elegant rather than loud, which is hard to do with pink. Text at 12:1; the active bar holds dark text at 5.5:1, the lowest on the list but still clearly readable.
Plum Velvet
#241B2E,#2F2440,#D8A7FF,#1C1424,#3A2D4D,#E6DAF0,#7CE0A0,#FF8FA3
A deep plum that's lighter and more purple than Pitch Violet, with a lilac active channel and mint presence dot. If Slack's old aubergine default was too brown for you, this is the modern version. Text at 12:1, active bar text at 9:1.
Forest Floor
#161F17,#1F2B20,#8FBF6A,#0F160F,#28372A,#CDD9C5,#6FD6B0,#F4A261
Near-black green with a moss active bar, a pale-sage text color, and an apricot badge, the one warm accent so alerts don't vanish into the green. Text at 11.5:1.
Arctic Black
#0A0F14,#111820,#7DD3FC,#06101A,#1A232D,#BCCBD6,#4ADE80,#F472B6
Black with a cold blue undertone, icy cyan active channel, and pink badge. Sits between the OLED set and the deep-color set: dark enough to look off on OLED, tinted enough not to feel like a void. Text and active bar both at 11.5:1, the most evenly readable string here.
Warm Slack Dark Themes
Most dark themes are cool. These two go warm, which makes a surprising difference in a dim room.
Ember Night
#1C1210,#271A16,#FF6B35,#1C1210,#33231E,#EAD9D0,#9CD67E,#FFD166
Deep reddish-brown with a flame-orange active bar and a gold badge. The highest text contrast on the list at 13:1 because the text is a warm off-white, not grey. Pairs well with a warm-shifted display at night.
Mocha Night
#1E1612,#2A1F19,#C68F5C,#1A120E,#36291F,#E6D8CC,#9ACD7A,#FF6F61
Espresso brown with a caramel active channel and cream text. Quieter than Ember Night; the accent is tan rather than orange. Text at nearly 13:1. Try it when every blue dark theme starts looking the same.
Pairing a Dark Theme With Slack's Dark Mode
A custom string colors the sidebar only. The message pane follows the light/dark mode setting in the same Appearance panel, and Slack will happily show a black sidebar next to a white message area. Turn dark mode on, then paste. With Sync with system, the sidebar stays put when the OS flips modes but the message pane goes light at sunrise, which looks odd next to true black. Pick a fixed dark mode for those.
If you hoped a dark theme would reach into message bubbles, fonts, or the top bar, it doesn't; that's a skin, and our post on Slack skins explains why those don't exist. Mobile apps ignore custom themes entirely.
Troubleshooting a Dark Theme That Won't Apply
Three things cause almost every failed paste. A malformed string: eight slots of # plus six hex characters, comma-separated, no spaces, no trailing comma; shorthand like #FFF breaks it silently. The wrong workspace: themes are per-workspace, so switch and paste again. Or you changed the sidebar but not the mode and only half the app looks dark. The longer checklist, including stale cache and out-of-date apps, is in Slack theme not working.
One quick plug while you're in the sidebar, with the bias stated: Propsly is ours. It adds peer recognition to Slack, so anyone types /props +20 @maria for the clean migration #teamwork and every give lands in a public feed channel. Free for unlimited users with 200 props per person a month. A good dark theme makes the sidebar easy to look at; a #wins channel lighting up inside it is what makes it worth looking at.
Common Questions About Slack Dark Themes
Does a true-black Slack theme save battery?
On an OLED display, yes, a little: black pixels are switched off. On an LCD the backlight is on regardless, so the only benefit is the look.
Is a black Slack theme worse for eye strain than dark grey?
For some people, yes. Very bright text on pure black can appear to halo or bleed, especially in a dark room. Keeping the text slot a light grey (as the OLED themes above do) rather than #FFFFFF helps a lot. If it still bothers you, use a charcoal theme instead.
Can I make the whole Slack window black, not just the sidebar?
Not with a theme string. Dark mode darkens the message pane to Slack's own grey, and custom strings color the sidebar. There's no supported way to set the message pane to pure black.
Why does my dark theme look different from the preview image?
Monitor calibration, mostly. Dark colors a few hex values apart look identical on one screen and clearly different on another. Live with it for a day, then nudge the background slot a step if needed.
Will my coworkers see my dark theme?
No. Themes are stored per person and per workspace. To get the team on one palette, post the string in a channel and let them click the button.
The Short Version
Turn on dark mode first, then paste one of the fifteen strings above. OLED screen and a taste for stark: Void, Obsidian Ember, Pitch Violet, or Carbon Fiber. LCD or sensitive eyes: Slate Night, Ash, Smoke & Brass, or Steel Blue. Want color without brightness: the deep-color and warm sets. Every string here keeps channel-name text at 7:1 or better against its background, so none of them will have you squinting. If you'd rather match your editor, the developer themes are the next stop; if it's December, the Christmas themes have a couple of dark ones too.