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Signal vs Slack

Signal logo

Signal

Software

Speak Freely

From
Free
Rated
-
Full reviewWebsite
Slack logo

Slack

Software

Where work happens

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Signal signal must be installed on a phone before the desktop app can be used, so there is no phone-free desktop-only account; Slack 90-day message history limit on free plan results in important conversations disappearing
  • They diverge on capability: Signal covers End-to-end encryption, Slack covers Channels.

Where they differ

Only the attributes on which Signal and Slack actually diverge.

Attributes where Signal and Slack differ
AttributeSignalSlack
Pricing modelfreeUnknown
PlatformsWindows, Macos, Linux, Ios, AndroidWeb, iOS, Android, macOS, Windows, Linux
Founded20102009

Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated), category (Unknown).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Signal

  • End-to-end encryption
  • Disappearing messages
  • Screen security
  • Group chats
  • Voice calls
  • Video calls
  • No data collection
  • Open source protocol

Only in Slack

  • Channels
  • Direct messaging
  • Voice & video calls
  • Screen sharing
  • Search
  • Workflow builder
  • Slack Connect
  • Google Drive

Both cover

  • File sharing

What people use each for

The jobs each tool is most often brought in to do.

Signal

  • Private messagingnot Slack
  • Secure group communicationnot Slack
  • Confidential conversationsnot Slack
  • Journalism communicationnot Slack
  • Family messagingnot Slack

Slack

  • Team communicationnot Signal
  • Project coordinationnot Signal
  • Customer supportnot Signal
  • Remote worknot Signal
  • Cross-functional collaborationnot Signal

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Signal

  • Signal must be installed on a phone before the desktop app can be used, so there is no phone-free desktop-only account

Slack

  • 90-day message history limit on free plan results in important conversations disappearing
  • Per-user pricing becomes expensive quickly for larger teams
  • Notification overload with 78% of employees feeling overwhelmed by notifications
  • Mobile app performance issues including lag and slow syncing
  • Huddles limited to 50 people and cannot be recorded
  • Requires dedicated video conferencing service for formal meetings and webinars

Pricing, plan by plan

Signal

Free
  • FreeFree
    • End-to-end encrypted messaging
    • Voice and video calls
    • Group chats

Slack

Free

No published plan breakdown. See the Slack review.

Which should you pick?

Choose Signal if

  • You need end-to-end encryption.
  • You want to start without paying.
  • You work on Windows, Macos, Linux, Ios, Android.
  • You also want disappearing messages.
Signal review

Choose Slack if

  • You need channels.
  • You want to start without paying.
  • You work on Web, iOS, Android, macOS, Windows, Linux.
  • You also want direct messaging.
Slack review

Questions people ask

Is Signal or Slack better?
Neither clearly leads. Signal starts at Free and Slack at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Signal or Slack?
Signal starts at Free and Slack at Free.
Does Signal or Slack run on more platforms?
Signal runs on Windows, Macos, Linux, Ios, Android. Slack runs on Web, iOS, Android, macOS, Windows, Linux.
Can I use Signal for free?
Both have a free tier, so you can try either at no cost before committing.
What is Signal best used for?
Signal is most often used for private messaging, secure group communication, confidential conversations, journalism communication. Of those, private messaging and secure group communication are not what Slack is typically brought in for.
What can Signal do that Slack cannot?
Signal covers End-to-end encryption, Disappearing messages, Screen security, Group chats. Slack covers Channels, Direct messaging, Voice & video calls, Screen sharing. Both handle File sharing.

Answered from the vendors’ own pages

Slack: Does Slack have a free plan?

Yes, Slack offers a free plan indefinitely with no credit card required. Free users get 90-day message history, up to 10 app integrations, and 1:1 huddles.

Source
Slack: What are Slack's pricing plans?

Slack offers Free, Pro ($7.25/user/month with annual billing), Business+ ($12.50/user/month), and Enterprise Grid (custom pricing). Monthly billing costs approximately 20% more than annual.

Source
Slack: Does Slack support offline use?

Slack is a cloud-based platform and does not support robust offline work. Internet connectivity is required to access messages and collaborate.

Source
Slack: What integrations does Slack support?

Slack integrates with 43+ apps on average per team, including Google Drive, ChatGPT, Vercel, Asana, GitHub, and many others through their app marketplace.

Source
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Related pages

More on Signal

More on Slack

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