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Instant messaging software lets people exchange messages over the internet in real time or near real time, while tracking conversation activity such as delivery or availability where supported. The category includes personal messaging apps, workplace chat, collaboration suites, and self-hosted systems; the right choice depends on who needs to communicate, what data must be protected, and whether the organization needs to retain or search messages.
What is instant messaging software?
Instant messaging (IM) software is a system for exchanging messages over the internet and following the progress of a conversation. The National Institute of Standards and Technology defines instant messaging as a facility for exchanging messages in real time with other people over the internet and tracking conversation progress: NIST’s instant messaging definition.
“Real time” describes the interaction model, not a guarantee that every message arrives instantly. A service may queue messages while someone is offline, then synchronize them across devices. Conversations can be live, but they can also continue asynchronously as participants reply later.
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- Protocol: Rules for exchanging messages, identities, encryption, and synchronization.
- Client: The web, desktop, or mobile app a person uses.
- Service: The servers, identity system, storage, administration tools, and commercial offering behind the client.
Two apps that both look like chat software may use different protocols and services, and users on one service usually cannot freely message users on another.
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Types of instant messaging software
Choose by purpose before comparing brands: software designed for personal privacy has different priorities from a workplace system that needs administration, retention, or project organization.
| Category | Primary purpose | Representative examples |
|---|---|---|
| Consumer messaging | Personal conversations with friends, family, or communities. | Signal, WhatsApp, iMessage, Messenger |
| Workplace team chat | Internal communication organized around teams, projects, channels, or rooms. | Slack, Microsoft Teams, Google Chat |
| Unified collaboration | Chat combined with meetings, files, calendars, email, and productivity services. | Microsoft Teams, Zoom Workplace |
| Self-hosted or sovereign chat | Greater control over hosting, data location, customization, or network access. | Mattermost, Rocket.Chat, Matrix-based deployments |
| Developer and operations chat | Coordination around code, incidents, infrastructure, and technical support. | Slack, Mattermost, Rocket.Chat |
| Customer messaging | Communication between organizations and customers across messaging channels. | Omnichannel products and messaging integrations |
Common features and what they do
Not every product includes every feature, and similar-sounding features can behave differently across plans and deployments. Check the exact coverage that matters to your use case.
| Feature group | Examples | Why it matters |
|---|---|---|
| Messaging | Direct and group messages; channels or rooms; threads; replies; reactions; mentions; pins; drafts; editing and deletion; scheduled or disappearing messages; read receipts and typing indicators. | Determines how well the service handles quick exchanges, structured work, and conversation context. |
| Presence and identity | Online, away, busy, and do-not-disturb states; custom status; directory search; guest access; contact discovery; account recovery and device management. | Helps people find colleagues and coordinate, but exposes availability and identity information. |
| Files and media | Images, video, documents, links, and code snippets; previews; malware scanning; storage integrations. | Check file-size limits, retention and deletion behavior, and whether attachments remain after a conversation or account is deleted. |
| Calls and meetings | Voice and video calls, screen sharing, meeting rooms, captions, recordings, and transcripts. | Calling features may change when end-to-end encryption is enabled; recording or transcription may not be available. |
| Search and retrieval | Full-text search across chats, channels, threads, and files; archives, exports, and AI-generated summaries. | Search scope depends on permissions and retention, and organizational access may be subject to policy or legal hold. |
| Integrations and automation | Calendars, document storage, CRM, project tools, code repositories, help desks, bots, APIs, webhooks, and workflows. | Integrations can reduce app switching but add permissions and third-party data flows to govern. |
| Administration | Single sign-on, provisioning, role controls, retention, audit, export, and external-user management. | Often the key distinction between a consumer app and a service suitable for an organization. |
Integration counts and catalogs change. Slack’s pricing page advertises more than 2,600 app integrations, a vendor-reported marketplace count that should not be treated as a fixed measure of integration quality: Slack pricing and plan information.
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| Channel | Typical model | Where it is useful | Important qualification |
|---|---|---|---|
| Internet messaging apps | App accounts, direct or group conversations, and often presence, media, and cross-device history. | Quick personal or workplace coordination. | Features, encryption, and interoperability vary by product. |
| SMS | Carrier-based text messaging tied to phone numbers. | Basic messages and broad phone reach. | Modern mobile messaging blurs the boundary with internet messaging; security depends on the implementation and route, so do not assume every app is encrypted or every SMS path has the same security properties. |
| Address-based, durable, asynchronous messages. | Formal communication, longer explanations, and records designed to persist. | Less oriented around presence and rapid conversational turns, although email can be read and answered quickly. | |
| Social media | Feeds, profiles, and public or semi-public content, sometimes alongside direct messages. | Publishing to an audience and community discovery. | Direct-message features can resemble chat, but the broader service is organized around audiences and content. |
| Video conferencing | Real-time audio and video meetings. | Conversation that benefits from voice, visual cues, or live presentation. | Many products include chat too; chat is more suited to persistent, searchable, asynchronous coordination. |
Security and privacy: understand the encryption layers
Encryption in transit
Encryption in transit protects data while it travels between a user’s device and a service, or between service components. TLS is commonly used for this layer. It does not, by itself, mean that the provider cannot access message content.
Encryption at rest
Encryption at rest protects stored data on servers or storage systems. A provider may still be able to decrypt content while operating features such as search, moderation, retention, or compliance review.
End-to-end encryption
In end-to-end encryption (E2EE), message content is encrypted so that only intended endpoints can decrypt it. Properly implemented E2EE is designed to prevent the service provider from reading that content. It is not a complete privacy guarantee: metadata such as account identifiers, contacts, timestamps, device details, IP addresses, or group membership may remain visible. Backups, notifications, unlocked devices, screenshots, copied text, and content reported by a participant can also expose messages.
Check precisely which conversation types, calls, files, devices, and backups receive E2EE. For example, Microsoft documents E2EE for selected Teams calling scenarios, while noting that some functions—including recording, transcription, call transfer, call merge, and adding participants—are unavailable during an E2EE call: Microsoft Teams E2EE details. Microsoft’s user guidance also describes using E2EE for supported Teams calls: Microsoft support guidance for Teams calls.
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Security risks beyond encryption
- Phishing links, malicious attachments, impersonation, and account takeover.
- Excessive guest access, weak administrator controls, and sensitive information posted in the wrong channel.
- Abuse of third-party integrations, OAuth permissions, bots, or webhooks.
- Personal or unmanaged devices, exposed notification previews, and backups with weaker protections than the primary service.
- Disappearing-message expectations defeated by screenshots, copying, exports, or retention settings.
- Incomplete E2EE coverage, such as protected text but unprotected calls, files, backups, or metadata.
- Consumer apps adopted for work without organizational controls, creating shadow IT and fragmented records.
The UK National Cyber Security Centre advises organizations to evaluate a messaging app’s security properties and trade-offs rather than infer suitability from a product name: NCSC guidance on choosing a messaging app for an organization.
Enterprise features to evaluate
For organizational use, confirm that the product’s controls match actual policy, legal, and operating requirements. “Enterprise-grade” is not a substitute for checking feature scope, configuration, and contractual terms.
- Identity: Single sign-on, multi-factor authentication, automated provisioning and deprovisioning such as SCIM, account recovery, and role-based administration.
- Access: Guest and external-user controls, channel governance, device policies, mobile-device management, and delegated administration.
- Records: Retention schedules, audit logs, legal hold, e-discovery, export APIs, and clear deletion behavior for messages and files.
- Data controls: Data residency, customer-managed keys where required, data-loss prevention, information barriers, and malware or phishing defenses.
- Operations: Support commitments, service availability, incident response, backup and recovery, and the ability to migrate data out.
Microsoft documents Teams encryption in transit and at rest, identity controls through Microsoft Entra ID, and audit, content search, legal hold, e-discovery, and related capabilities through Microsoft Purview: Microsoft Teams security and compliance overview. This illustrates why E2EE and enterprise governance can pull in different directions: provider-side searching, retention, moderation, or e-discovery over message content generally requires the service to access that content. The suitable design depends on the threat model and applicable obligations.
Protocols, interoperability, federation, and self-hosting
Open protocols are not the same as open apps
XMPP is an open protocol family for messaging and presence. Matrix is a decentralized communication protocol and ecosystem. Messaging Layer Security (MLS) is an IETF architecture for end-to-end security in group messaging; it is not a complete user-facing chat app or service, but is intended to be embedded in concrete protocols and applications: RFC 9750 on Messaging Layer Security architecture.
Why services do not automatically interoperate
Connecting systems is difficult because they may differ in identity, group membership, message ordering, synchronization, media, moderation, retention, and encryption. A bridge or integration may carry basic text while losing threads, reactions, edits, read receipts, calls, permissions, or encryption guarantees. Ask which capabilities survive the connection and whether identity verification, abuse reporting, and retention still work as intended.
Deployment models
- Centralized SaaS: A vendor operates the service. It is generally quick to deploy and reduces infrastructure work, but brings vendor dependence, subscription costs, and constraints around data architecture and exit.
- Federated: Multiple servers or organizations can communicate using shared protocols. Federation can improve autonomy and reach, but may complicate identity, administration, and consistent features.
- Self-hosted: The organization or a contracted provider operates the software. It offers greater control and customization, while shifting upgrades, security response, backups, availability, monitoring, abuse prevention, mobile push, compliance configuration, recovery, and user support to the operator.
- Hybrid: Some components are vendor-hosted while identity, storage, or encryption keys remain under organizational control.
Mattermost positions its offering around controlled collaboration, supports self-hosted deployments, and lists integrations with external video services: Mattermost plans and deployment information. The additional control is useful only if the organization can operate or manage the deployment reliably.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How to choose instant messaging software
- Define the main use. Separate personal communication, internal team chat, customer support, incident response, frontline work, regulated communications, developer operations, and community messaging.
- Set the security requirement. Decide whether E2EE is required, preferred, or unnecessary; identify whether administrators must search or retain messages; determine whether personal devices and offline access are allowed and whether metadata is sensitive.
- Map users and connections. Count employees, guests, external organizations, contractors, and temporary users. Check whether several business units or tenants need to collaborate and whether federation is necessary.
- Check governance needs. Verify SSO, MFA, provisioning, audit, retention, legal hold, e-discovery, export, data residency, guest controls, and device management against actual requirements.
- Match the collaboration depth. Compare chat, meetings, files, calendars, search, workflows, AI features, and integrations. A suite may simplify existing work, but can add complexity or spread data across connected services.
- Choose the operating model. Compare SaaS, private cloud, on-premises, self-hosted, and federated options against data-control requirements and the staff available to maintain them.
- Test adoption and usability. Pilot mobile use, notifications, accessibility, onboarding, search, external collaboration, and performance on weak networks. A difficult system can push people toward less-governed channels.
- Calculate total cost and exit effort. Include seats, guests, storage, AI, meetings, recordings, compliance features, support, migration, administration, hosting, backups, disaster recovery, and export or termination costs.
Representative products by use case
These are category matches, not a universal ranking. Product features and plans change, so confirm current terms with the vendor before choosing.
Quick Recap
| Product | May fit when | Check before selecting |
|---|---|---|
| Slack | Teams want channel-based workplace chat, workflows, searchable history, and a broad integration ecosystem. | It is not a fit when complete self-hosting or provider-independent federation is required. The Free plan limits searchable history to 90 days and apps to 10 according to its pricing page; paid plans offer broader capabilities. Plan limits and prices can change: Slack pricing. |
| Microsoft Teams | An organization already uses Microsoft 365, Entra ID, SharePoint, Exchange, or Purview and wants chat integrated into that environment. | Check which capabilities are included in the organization’s existing licensing, how data is distributed across connected services, and which scenarios support E2EE. |
| Zoom Workplace / Zoom Chat | Meetings are already centered on Zoom and chat is wanted within the same suite. | Its value may be lower if the organization does not use Zoom meetings; check plan, region, user range, and add-ons on the official Zoom Chat page. |
| Mattermost | Technical, security-sensitive, or operational teams need a controlled or self-hosted collaboration environment. | Assess staffing for deployment, upgrades, monitoring, backups, and recovery, and obtain current plan details from Mattermost. |
| Rocket.Chat | A team wants customizable or self-managed chat, potentially including omnichannel communication. | Rocket.Chat states that its Pro plan was retired for new purchases effective April 29, 2026; verify the current plan structure and fit before procurement: Rocket.Chat plan documentation. |
| Signal or WhatsApp | Personal, small-group, or lightweight external communication is the main need. | Consumer messaging apps are generally a poor substitute for organizational systems that require centralized retention, e-discovery, provisioning, or formal audit. |
Common selection mistakes
- Equating “encrypted” with E2EE. Confirm whether the claim means transport, storage, or endpoint-to-endpoint protection, and which message types it covers.
- Assuming deletion means erasure. A message may disappear from a user’s view yet remain under retention, legal hold, export, or backup policies.
- Choosing by free-tier price alone. History, apps, storage, administration, meetings, and support may be limited. Free does not necessarily mean low long-term cost.
- Ignoring external users. Guests, partner organizations, and contractors can affect access design, licensing, retention, and collaboration quality.
- Underestimating fragmentation. Multiple chat services alongside email and project tools can duplicate notifications, scatter context, and create inconsistent records.
- Overlooking the exit plan. Ask whether exports include private messages, files, threads, reactions, edits, and metadata, what format they use, and whether users retain access after termination.
- Self-hosting without operating capacity. Control does not remove the need for patching, monitoring, backup, security response, and disaster recovery.
- Using consumer apps as shadow business systems. Informal convenience can conflict with company policy, regulated retention, and identity lifecycle management.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
