Choosing a work messaging app

What is actually on the market

Team chat has consolidated around Microsoft Teams, Slack and Google Chat, with independent products aimed at specific gaps. Nearly every organisation ends up with one of a short list, and the differences between the leaders are smaller than the comparisons suggest.

• Microsoft Teams. Available in Microsoft 365 plans with Teams and as a separate purchase. Check your exact licence: Microsoft also sells plans without Teams. It is a natural shortlist choice where the organisation already uses Microsoft identity, files and meetings
• Slack. The reference point for the category. Better at channels, search and third-party integration; a separate purchase and a separate identity to manage
• Google Chat. Included with Google Workspace. Simpler than either, and sensible if your organisation already lives in Google
• The independents. Products aimed at specific gaps: frontline and deskless teams, sectors with particular requirements, or organisations wanting to self-host

Compare the messaging platform with the work tools your people already use. Slack organises team messaging around channels and connects to other services through its app directory. Microsoft Teams brings chat, meetings and Microsoft 365 files together where the licences include those services. Google Chat is a natural candidate for Google Workspace users who already share documents there. Check the integrations you actually need, rather than treating the length of an app directory as a measure of fit.

For general internal communication and team collaboration, start with the team chat app included in the productivity suite you already pay for. Test it with your people before buying a second system. The best fit depends on the participants and the work, not on which supplier leads a list of business messaging apps.

That advice changes only when the messages themselves have to be producible later. That is a different requirement, and it is covered further down.

You probably already own one

A common mistake is buying a communication app that duplicates something already included in a licence the organisation pays for. Check whether your Microsoft 365 subscription includes Teams, and whether Google Chat is available under your Google Workspace setup. Microsoft's current plan comparison distinguishes plans with and without Teams. Owning Microsoft 365 alone does not settle it.

This matters beyond the licence cost. A second messaging app means a second directory of who works here, a second set of leavers to remember, a second place to search when someone asks a question, and a second supplier holding your data. Organisations that end up with both usually did not decide to; the second arrived with a department.

The exception is not a small one, and it is why the advice above is qualified rather than general. Teams and Slack both assume that everyone in the conversation has an account on your systems. A great many of the people organisations actually need to talk to do not.

Frontline and deskless staff are the first group: care workers, cleaners, caterers, drivers, teaching assistants, bank and agency staff, volunteers. Many have no work email address, and issuing a full productivity licence to each of them so they can be told that a shift has changed is an expensive way round a simple problem. The second group is larger still and is usually forgotten at this stage entirely: the people the organisation exists to serve. Residents and their families, tenants, clients, parents. Guest access in the mainstream products was built for a contractor joining a project, not for a daughter asking about her mother, and it requires an account either way.

Where that describes your situation, the deciding feature is what the product accepts as an identity. One that can treat a verified mobile number as the identity lets a bank carer, a volunteer or a family member take part without an account being created for them on your systems. That single design choice determines whether half your intended participants can join at all, and no feature comparison lists it.

Before you compare products, write down who has to be in the conversation, including the people outside your organisation. If a third of them have no work email address, that single fact will decide more than any feature list.

What to compare, once you have a shortlist

Check the basics on the plan you will use. Instant messaging apps for business commonly offer group chats, direct messages, file sharing and search, but voice and video calls, video conferencing, screen sharing, task management and automation vary by product and tier. Do not infer that a free version includes every feature on the supplier's homepage. The differences that affect daily business communication go beyond a feature tick.

• How it handles notifications. The single largest driver of whether people keep it open. Look at how granular the controls are, and whether quiet hours are respected on mobile
• Identity and joiners and leavers. Does it use the identity you already run, so that removing someone removes them everywhere?
• Guests and external people. Almost every organisation needs to talk to someone outside it. Check what a guest can see, and what happens to that access when the project ends
• Search. Whether you can actually find a decision from eight months ago, which is a question about retention as much as about search quality
• Integration. Both with your productivity suite and with the handful of tools your organisation genuinely depends on. Do not weight a directory of hundreds of integrations you will never connect
• Voice channels and presence. Useful for in-office teams who want an always-open room to drop into, and largely irrelevant to a distributed shift-based workforce
• Where it stops. Team chat is not project management, and products that try to be both tend to be a weaker version of each

Weight all of that against your own use case rather than against a review's scoring. The best app for a software team in one office is rarely the best instant messaging app for a charity with sixty volunteers, and roundups of the best work chat apps are written for the first. Run the shortlist with a real team for a fortnight rather than in a demonstration. Chat products fail on habit rather than on features, and habit does not show up in a feature grid.

For a practical workplace messaging test, use fictional material: invite someone without a work email, share files, mute a busy group, find an earlier decision and remove a test member. Check both a phone and a browser. If work communication includes people on personal devices, ask whether other members can see their mobile numbers and whether they can control notifications outside working hours. These checks say more about everyday use than another office chat feature list.

Map one team communication workflow from start to finish. Who raises a question, who answers it, and where does the agreed action go? Colleagues may collaborate in chat while the final action belongs in a care, safeguarding or case-management system. Check how information reaches that system, who is responsible for filing it and whether the integration costs extra. Collaboration software is useful only if it supports that division of work.

Check the audience of each conversation too. Private and public channels can mean different things in different chat platforms: visible to everyone in a workspace is not the same as accessible from the public web. Use test identities to check who can discover a channel, read old messages and invite another person. A product's name for a channel is not evidence of its access rules.

What a free plan does to your message history

This is the criterion buried in the pricing table, and it surprises organisations later.

A free plan can limit message history, the number of members, guest access or administrative controls. These are separate limits. An offer of unlimited users says nothing about how long messages remain available; unlimited message history says nothing about who can export it or impose a retention period. Read the limits for the specific plan.

Separate hidden history from deleted history. Slack's free-plan guidance, checked in September 2026, describes access to the latest 90 days of message and file history and deletion of material older than a year. An upgrade can reveal older material that still exists; it cannot recover material already deleted. Ask every supplier which of these states applies, whether export is available before expiry, and what happens if you downgrade again.

Two consequences follow. The first is legal rather than commercial: if the organisation might have to produce a conversation, whether for a subject access request, an employment matter or a regulator, a plan that hides history at ninety days and deletes it after a year has made that harder and then impossible, while looking like a saving. The second is institutional memory: the reasoning behind a decision is usually in the thread, and a rolling window quietly deletes your own explanation of why you did things.

The mirror image is also a problem. Keeping every personal conversation indefinitely without a reason creates an accumulating liability. The ICO's storage limitation guidance calls for retention justified by purpose. Look for a period your organisation can choose, applied automatically, with a way to preserve specific material when it is needed for an active matter.

Ask the supplier two questions: what is the default retention on the plan we are actually buying, and can we set it ourselves. Include export permissions and any extra cost in the answer. Before moving business chat to a different service, check whether the old chat history can be exported with participants, dates and attachments, and where your organisation will keep that export. Opening a new channel does not migrate old evidence.

The question the comparisons never ask

Everything above is about workplace communication as a productivity problem. For a large minority of organisations there is a second requirement, and no comparison of the best work chat apps covers it: if someone asked, could we produce this conversation?

That question arrives from three directions. A regulator asking what was decided and when. A subject access request, where a person is entitled to the personal data in messages about them, with a one month clock. Or litigation and employment tribunals, where the other party usually has their own copy already.

The organisations that need to answer it are more numerous than the phrase regulated industries suggests: schools and trusts, charities, care providers, housing associations, professional bodies, and anyone whose staff discuss individuals in the course of their work. If your people talk about named children, residents, tenants or clients in a chat app, you are in this group whether or not you think of yourself as regulated.

For those organisations the criteria change. The record has to be made by the service rather than assembled from handsets. It has to survive the person leaving. It has to be searchable by the organisation, not only by the participants. Retention has to be yours. And where the record ends up matters as much as that it exists: a record held only in a supplier's cloud is one you have to ask a third party for at exactly the moment you are short of time.

The related question is transparency. If conversations are kept, everyone in them should be told plainly and at the outset. Organisations worry that staff will object; in practice people object to discovering it, not to being told.

A short way to decide

Three questions, in order, will settle most of it.

1. Who has to be in the conversation? If every one of them has a work account on a suite you already pay for, use what that suite includes and stop. If frontline staff, volunteers, service users or families are on the list, ask what the product accepts as an identity before you ask anything else
2. Might we ever have to produce one of these conversations? If no, buy on usability and price. If yes, the requirements in section 05 apply and most general chat products do not meet them
3. What happens to the history? Check the retention on the plan you are buying, not the plan on the marketing page

It is entirely reasonable to answer the second question with no. Most teams, most of the time, are coordinating work rather than making decisions about people, and a good instant messaging app bought on usability is the right purchase. The failure worth avoiding is answering no by not asking.

ComplyChat illustrates the distinction. Its Free personal plan has one private group, direct messages and up to 25 staff members. Only the owner invites staff; there is no guest invitation route on Free. Signup needs a UK mobile number, but no card or Microsoft account. You can use the browser app to get to know it before deciding whether your organisation needs a paid plan.

Free history expires after three calendar months from each message. This is not a fixed 90-day window, and upgrading cannot restore expired history. Free has no Microsoft 365 archive or Replay. Paid ComplyChat plans add Microsoft Teams and meet your retention schedules within your own Microsoft 365 subscription once the archive is connected and filing. A personal conversation space and a lasting organisational record serve different purposes: choose the latter before the conversations you need to retain take place.

Further reading

The ICO covers storage limitation and subject access, which are the two data protection points that bear on this choice, and its employment practices material covers being transparent with staff. For a general feature comparison, the large independent reviews of the best work chat apps are genuinely useful and update yearly, including their roundups of Slack alternatives; use them to build the shortlist and this guide for the questions they do not ask.

This page is a buying guide rather than legal advice, and whether your organisation falls into the group described in section 05 is worth confirming with whoever advises you on data protection.