In this guide · 8 sections
Short answer
If you already pay for Microsoft 365, use Teams: it is included. If your team lives in Google Workspace or uses many apps, Slack Pro (US$7.25 per user a month, yearly) is the better chat tool. Keep WhatsApp Business for customers, not for internal work you need to keep.
The quick comparison
Prices are per user per month in US dollars, before GST, from Slack's Singapore pricing page and Microsoft's Teams Essentials page and Microsoft 365 business plans page, as of October 2026. We have not run our own tests; this comparison is based on vendor documentation.
| WhatsApp (groups) | Slack | Microsoft Teams | |
|---|---|---|---|
| Price | Free | Free; Pro US$7.25 (yearly) or US$8.75 (monthly); Business+ US$15 (yearly) | Essentials US$4.00 (yearly); included in Microsoft 365 Business Basic at US$7.00 |
| Message history | On each person's phone and backup | Free: 90 days. Paid: unlimited | Kept in the company's Microsoft 365 tenant |
| Who controls accounts | Each employee | The business (workspace admin) | The business (Microsoft 365 admin) |
| Video meetings | Calls, small groups | Free: 1:1 huddles. Paid: group huddles | Up to 300 participants, up to 30 hours (Essentials) |
| Best for | Talking to customers | Teams using many apps or Google Workspace | Businesses already on Microsoft 365 |
WhatsApp groups: free, familiar and hard to control
WhatsApp's strength is that nobody needs training. Its weakness for internal work is that every chat belongs to a personal phone number. When an employee leaves, you can remove them from groups, but everything they already received stays on their phone: customer details, photos of invoices, passwords someone pasted into the group.
- No central admin: you cannot wipe a leaver's copy of the chats or reset their account.
- Search and history depend on each person's phone and personal backup.
- Lost or hacked phones expose every group. See our guide to a hacked WhatsApp or social media account.
- Mixing personal and work makes it easy to send something to the wrong chat.
For customer conversations, the WhatsApp Business app is still a good tool. WhatsApp's help centre says you can use it on up to four linked devices without keeping the primary phone connected, and up to 10 with a Meta Verified subscription, which lets staff answer from a shared account rather than personal numbers.
Slack: the best pure chat tool
Slack organises work into channels, such as #sales or #deliveries, so conversations do not all pile into one group. The business owns the workspace, adds and removes people, and can connect over 2,600 apps, according to Slack's pricing page.
The Free plan is fine to try, but messages are only saved and searchable for 90 days and you are limited to 10 apps. Pro (US$7.25 a month per user, paid yearly) removes those limits and adds group huddles and shared channels with outside partners. Slack offers 50% off for three months on monthly Pro or Business+ plans bought online within seven days of creating a workspace.
Slack is not an email or file system. You still need Microsoft 365 or Google Workspace for mailboxes and documents, so it is an extra cost on top.
Microsoft Teams: free if you already have Microsoft 365
If your business email runs on Microsoft 365 Business Basic, Standard or Premium, Teams is already included. Accounts are your Microsoft 365 accounts, so when you disable a leaver's account, their access to Teams chats and files ends at the same time.
For businesses not on Microsoft 365, Teams Essentials costs US$4.00 per user a month paid yearly and, per Microsoft, includes unlimited chat with guest access, meetings of up to 300 people for up to 30 hours, and 10 GB of cloud storage per user. Teams feels heavier than Slack, but for a business already using Outlook, Word and Excel it keeps everything in one place. Our Microsoft 365 vs Google Workspace comparison covers the bigger choice.
Which one should your business use?
Rules of thumb
Whichever you choose, write down where work conversations should happen, and move them there. A tool only helps if people stop using the old WhatsApp group.
Security basics for any team chat
Turn on multi-factor authentication for Slack or Microsoft 365 admin and user accounts; our MFA set-up guide walks through it. Remove leavers on their last day. If staff use personal phones for work chat, set rules about screen locks and what can be shared; our BYOD policy guide explains how device management can separate work apps from personal ones.
Never paste passwords, NRIC numbers or card details into chat. Use a password manager for shared logins.
Do it yourself or get help?
Creating a Slack workspace or turning on Teams takes minutes. The harder part is the admin side: who can create channels, guest access, retention, and making sure leavers lose access.
Our Microsoft 365 / Google Security Lockdown (S$590) sets up MFA, admin roles, sharing and leaver controls across Microsoft 365 or Google Workspace, including Teams or Chat. If staff use their own phones, Device Encryption & Management (S$490) keeps work apps and data under the business's control.
Frequently asked questions
For a very small team it works, but chats live on each person's phone. When staff leave, they keep everything they received, and you cannot wipe it. For teams that share customer data or need a record of decisions, a business-controlled tool like Teams, Slack or Google Chat is safer.
As of October 2026, Slack Free costs nothing but keeps only 90 days of message history. Pro is US$8.75 per user a month paid monthly, or US$7.25 paid yearly. Business+ is US$18 monthly or US$15 yearly. GST applies on top.
Teams is included in Microsoft 365 Business Basic, Standard and Premium, so if you already pay for those there is no extra cost. On its own, Teams Essentials is US$4.00 per user a month paid yearly, before GST, as of October 2026.
If you already use Microsoft 365 for email, Teams is the sensible choice because it is included and uses the same accounts. If you use Google Workspace or rely on many third-party apps, Slack is generally easier to use. Both let the business control accounts and remove leavers.
Yes. WhatsApp says the Business app can run on up to four linked devices besides the primary phone, or up to 10 with a Meta Verified subscription, which also lets you assign chats to agents. The primary phone must be used at least every 14 days to keep linked devices connected.