Developer Tools · head to head
Keycloak vs Microsoft Outlook
Keycloak
Developer Tools
Open-source identity and access management server.
- From
- Free
- Free plan
- Yes
Microsoft Outlook
Technology
Microsoft's email and calendar client, in the middle of a transition from the classic Windows application to a web-based replacement.
- From
- Free
- Free plan
- Yes
The short version
- Each has a real cost: Keycloak requires self-hosted deployment and operational expertise to install, configure and maintain; Microsoft Outlook microsoft is replacing the classic Win32 client with the new web-based Outlook, and the new one runs only web add-ins, not COM add-ins, so any line-of-business integration for CRM, dictation, document management or telephony must be rewritten or the desktop stays on classic until its support window closes.
- Prices and features above were last checked on 30 August 2026.
Where they differ
Only the attributes on which Keycloak and Microsoft Outlook actually diverge.
| Attribute | Keycloak | Microsoft Outlook |
|---|---|---|
| Pricing model | open-source | freemium |
| Platforms | Self-hosted, Docker, Kubernetes, Linux, Windows, API | Web |
| Category | Developer Tools | Technology |
Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated).
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 Keycloak
Nothing recorded that Microsoft Outlook does not also cover.
Only in Microsoft Outlook
- Exchange calendar integration
- Delegate access
- Shared mailboxes
- Rules and Quick Steps
- Retention, hold and eDiscovery
- Sensitivity labels and encryption
- Add-in platform
- Offline cached mode
What people use each for
The jobs each tool is most often brought in to do.
Keycloak
- Organisations requiring self-hosted identity infrastructure for compliance or data residencynot Microsoft Outlook
- Companies with existing LDAP/Active Directory systems needing federated authenticationnot Microsoft Outlook
- Open-source projects and communities requiring free IAM without licensing costsnot Microsoft Outlook
- Enterprises building custom identity workflows requiring fine-grained authorisationnot Microsoft Outlook
- Teams with sufficient operational expertise to manage infrastructurenot Microsoft Outlook
Microsoft Outlook
- Organisations on Exchange Online or Exchange Server where free/busy scheduling and room booking across everyone is a daily requirementnot Keycloak
- Executive assistants managing someone else's calendar and mailbox through delegate access, which no IMAP client supports properlynot Keycloak
- Regulated environments that need retention policies, legal hold and eDiscovery applied to mail centrally rather than per usernot Keycloak
- Teams handling shared inboxes such as support or accounts, where permissions and tracking matter more than the mail client itselfnot Keycloak
Where each one falls short
Documented limitations, not opinions. Every one is a constraint you would hit in normal use.
Keycloak
- Requires self-hosted deployment and operational expertise to install, configure and maintain
- No managed cloud option provided by Red Hat; organisations must operate infrastructure themselves or use third-party distributions
- Clustering and high-availability configurations require additional operational knowledge
- Community support only; commercial support requires third-party vendors or distributions
Microsoft Outlook
- Microsoft is replacing the classic Win32 client with the new web-based Outlook, and the new one runs only web add-ins, not COM add-ins, so any line-of-business integration for CRM, dictation, document management or telephony must be rewritten or the desktop stays on classic until its support window closes.
- The new client's handling of non-Microsoft accounts synchronises mail through Microsoft's cloud rather than connecting from the machine to the provider, which several organisations' data residency and handling policies do not allow, and it is not an optional behaviour.
- PST and OST files are a single-file, corruptible and effectively unshareable store, and the new client's reduced PST support means years of personal archives sitting in those files need an explicit migration plan rather than carrying forward.
- Large mailboxes turn software problems into administration ones: search index rebuilds, OST files of tens of gigabytes and the mailbox quotas of whichever plan was bought, and the usual fix is archiving policy rather than anything a user can do.
- Against IMAP or Gmail you lose most of what justifies it, including free/busy lookup, room booking, delegate access, and retention and compliance policies, because those are Exchange server features rather than client features.
- The five or six products sharing the Outlook name have materially different feature sets, so internal documentation, training and support procedures must be written per platform and a user moving between desktop, web and mobile finds the same task done differently in each.
Pricing, plan by plan
Keycloak
Free- Open-sourceFree
- Full platform functionality
- Self-hosted deployment
- Community support
Microsoft Outlook
Free- Outlook (Free)Free
- 15 GB mailbox storage
- 5 GB cloud storage
- Web and mobile Office app access
- Microsoft 365 Basic$1.99/month
- 100 GB mailbox storage
- 100 GB cloud storage
- Ad-free experience
- Microsoft 365 Personal$9.99/month
- 1 TB cloud storage
- Desktop Office apps (Word, Excel, PowerPoint, Outlook, OneNote)
- Copilot with high usage limits
- Microsoft 365 Family$12.99/month
- 1-6 users
- Up to 6 TB total cloud storage (1 TB per person)
- Same apps and features as Personal
Which should you pick?
Choose Keycloak if
- You want to start without paying.
- You work on Self-hosted, Docker, Kubernetes, Linux, Windows, API.
Choose Microsoft Outlook if
- You need exchange calendar integration.
- You want to start without paying.
- You also want delegate access.
Questions people ask
- Is Keycloak or Microsoft Outlook better?
- Neither clearly leads. Keycloak starts at Free and Microsoft Outlook at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
- Which is cheaper, Keycloak or Microsoft Outlook?
- Keycloak starts at Free and Microsoft Outlook at Free.
- Does Keycloak or Microsoft Outlook run on more platforms?
- Keycloak runs on Self-hosted, Docker, Kubernetes, Linux, Windows, API. Microsoft Outlook runs on Web.
- Can I use Keycloak for free?
- Both have a free tier, so you can try either at no cost before committing.
- What is Keycloak best used for?
- Keycloak is most often used for organisations requiring self-hosted identity infrastructure for compliance or data residency, companies with existing ldap/active directory systems needing federated authentication, open-source projects and communities requiring free iam without licensing costs, enterprises building custom identity workflows requiring fine-grained authorisation. Of those, organisations requiring self-hosted identity infrastructure for compliance or data residency and companies with existing ldap/active directory systems needing federated authentication are not what Microsoft Outlook is typically brought in for.
- What can Keycloak do that Microsoft Outlook cannot?
- Microsoft Outlook covers Exchange calendar integration, Delegate access, Shared mailboxes, Rules and Quick Steps.
Answered from the vendors’ own pages
Keycloak: What protocols does Keycloak support?
Keycloak supports OpenID Connect, OAuth 2.0 and SAML 2.0 protocols for authentication and authorisation.
SourceMicrosoft Outlook: What is the difference between classic Outlook and the new Outlook for Windows?
Classic is the long-standing Win32 application shipped with Microsoft 365 and Office LTSC. The new Outlook is a web-based client that replaced Windows Mail and Calendar. The most consequential difference is add-ins: the new client supports only web add-ins, not COM add-ins.
Keycloak: Can Keycloak integrate with existing user directories?
Yes. Keycloak supports user federation with LDAP and Active Directory systems, allowing organisations to leverage existing user directories.
SourceMicrosoft Outlook: How long will classic Outlook be supported?
Microsoft has stated support through at least 2029. That is a planning window rather than a reprieve, and organisations with COM add-in dependencies should be scoping the replacement work now.
Keycloak: Is Keycloak free?
Yes. Keycloak is fully open-source and free to deploy and use. No licensing fees are required.
SourceMicrosoft Outlook: Can I use Outlook with Gmail or another IMAP provider?
Yes, but with reduced capability. You lose free/busy lookup, room booking, delegate access and server-side compliance policies, because those come from Exchange rather than from the client.
Microsoft Outlook: Is Outlook free?
Outlook on the web and the mobile apps are free with a Microsoft account, and the new Outlook for Windows is included with Windows 11. The classic desktop application requires a Microsoft 365 subscription or an Office perpetual licence.
Microsoft Outlook: Will my COM add-ins work in the new Outlook?
No. The new client supports only the cross-platform web add-in model. Vendors must publish a web add-in, and where they have not, the choice is to stay on classic Outlook or replace the integration.
Related pages
More on Microsoft Outlook
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