Rainbow vs Slack (2026): which should you pick?

Pick Rainbow if

• Fits if your company already runs Alcatel-Lucent phones and wants chat on top
• Works for organisations that need to choose where their data sits

Look elsewhere if

• Skip it if you want a price on the page, as none is published
• Not for you if you are one person or a very small team, since it targets organisations
• Too light on detail for licences, because it is unclear which features come with which one
• Watch out: no trial or free plan is listed

Pick Slack if

• Fits if your team wants conversations sorted by channel instead of email threads
• Works for teams that share channels with outside partners or plug many apps into chat

Look elsewhere if

• Tight if you're staying free, as only 90 days of messages stay searchable and you get 10 apps
• Skip it if you want group huddles or Slack Connect for free, as both are 1:1 until Pro, which has no trial
• Pricey if you need single sign-on, SCIM or AI search, which start at Business+ for $15 a user a month
• Watch out: enterprise search and data loss prevention are on Enterprise+ at $45 a user, bought through sales
• Not for you if you'd run huddles in a browser other than Chrome or Firefox, as they aren't supported there

Rainbow

• No prices are published on the pages read; pricing is unverified and likely sold through Alcatel-Lucent Enterprise.
• The vendor describes an a la carte service, so which features come with which licence is not stated on the pages read.
• Rainbow is aimed at organizations, not individuals or very small teams.

Slack

• The Free plan keeps only 90 days of message history searchable, allows 10 apps, and limits huddles and Slack Connect to 1:1.
• SAML single sign-on and SCIM start at Business+; ongoing Slackbot access is on Business+ and Enterprise+, with a limited trial on Free and Pro.
• Enterprise search, multiple SAML configurations and native data loss prevention are limited to Enterprise+, listed at $45 per user / month paid annually and bought through sales.
• In a browser, huddles are supported only in Chrome and Firefox.

Rainbow

Chat and collaboration

Enterprise messaging and collaboration sit in the same app as business telephony and meetings.

AI services

The vendor lists transcription, summaries, real-time translation and an AI reception agent as included in the licence.

Flexible deployment

Runs as public cloud, on top of an existing PBX or as a private cloud, for 5 to 100,000 users according to the vendor.

Data location and certifications

The vendor lists 15 data centres worldwide and certifications including ISO 27001, GDPR, HIPAA and C5.

Microsoft Teams connector

A telephony connector pairs Rainbow with Microsoft Teams, and APIs and SDKs support custom integrations.

Apps for each platform

The vendor's pages list a web application plus apps for macOS, Windows, iOS and Android.

Slack

Channels and direct messages

Conversations are organized into channels for each project, topic or team, alongside direct messages. Paid plans keep the full message and file history searchable; Free keeps 90 days.

Huddles and clips

Huddles are audio and video meetings with screen sharing, 1:1 on Free and for groups on paid plans. Clips are recorded audio or screen updates shared in a conversation.

Slack Connect

Message people outside the company. Free allows 1:1 external direct messages; paid plans add group chats and shared channels with up to 250 organizations.

Canvases and lists

A canvas holds text, files, images and video inside Slack, and lists are used to manage projects and organize tasks with teammates.

Workflow Builder and apps

Workflow Builder automates routine processes without code, and the app directory lists more than 2,600 apps. A Free workspace can connect up to 10 of them.

AI in Slack

Pro includes AI conversation summaries. Business+ adds AI search, daily recaps, file summaries, workflow generation and the Slackbot personal agent, subject to plan limits.

Rainbow

Pricing could not be confirmed. See openrainbow.com.

Slack

• Free$0

  90 days of message history, up to 10 app integrations, and 1:1 huddles and external messages.

• Pro$7.25

  per user / month, billed annually ($8.75 billed monthly)

  Unlimited message history and app integrations, group huddles, Slack Connect channels with up to 250 organizations, and AI conversation summaries.

• Business+$15

  per user / month, billed annually ($18 billed monthly)

  Adds AI search, daily recaps, file summaries and workflow generation, the Slackbot agent, SAML single sign-on and SCIM user management.

• Enterprise+$45

  per user / month, billed annually

  Bought through sales. Adds enterprise search across connected apps, multiple SAML configurations, EMM support, native data loss prevention and unlimited workspaces.

Rainbow

No public discounts listed.

Slack

• Annual discount

  About 17% less with annual billing

  Pro is $7.25 per user / month paid annually against $8.75 paid monthly, and Business+ is $15 against $18. Salesforce's Slack pricing page puts the saving at approximately 16%.

• Other savings

  50% off the first 3 months for new teams

  A limited-time offer for teams that buy Pro or Business+ online within 7 days of creating the workspace. It applies to monthly billing only, and standard pricing follows after 3 months.

• Nonprofit

  Free or 85% off for eligible nonprofits

  Eligible nonprofits get a free Pro upgrade for workspaces with 250 or fewer members and 85% off above that size. Business+ is 85% off at any size.

• Education

  85% off for educational institutions

  The Slack for Education program gives approved institutions an 85% discount on the Pro or Business+ plan, applied at checkout.

• By country

  Lower price shown to buyers in India

  On October 9, 2026 Slack's pricing page showed a reader in India Pro at ₹245.25 per user / month paid yearly, beside a crossed-out ₹545. Its US page lists Pro at $7.25 per user / month paid annually.