Open Source Outlook.com AlternativesTop WebMail Providers & Email Clients like Outlook.com

The best open source alternative to Outlook.com is Proton Mail. If that doesn't suit you, our users have ranked more than 50 alternatives to Outlook.com and 16 is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to Outlook.com are Tuta Mail, Disroot, Posteo and Infomaniak kMail.

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Alternatives list

  1. Proton Mail icon

    Proton Mail

     1017 likes
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    Proton Mail provides secure email services with end-to-end encryption, ensuring data protection. Swiss-based and outside US jurisdiction, it offers a free version to champion privacy as a human right. Fully accessible on any device.

    98 Proton Mail alternatives

    Cost / License

    • Freemium (Subscription)
    • Open Source

    Application types

    Platforms

    • Mac
    • Windows
    • Linux
    • Online
    • Android
    • iPhone
    • iPad
    • Tor
    • Flathub
    • Snapcraft
    Proton Mail screenshot 1
     
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    25
    Comments about Proton Mail as an Alternative to Outlook.com
    plants
    Positive
    2

    It's not dissimilar to Tutanota. Both these projects are in their infancy, so technically neither is close to a mature product like Outlook, but still worthy of association under the broad category of hosted email-related services

    Oscar Sanderson
    Positive
    0

    I like protonmail because it is private and does not sell your data and is the best thing to switch to if you are using outlook

    Outlook.com Icon
    Proton Mail icon

    • Almost everyone thinks Proton Mail is a great Outlook.com alternative.

    • Proton Mail is the most popular Web-based, Windows, Android & Mac alternative to Outlook.com.

    • Proton Mail is the most popular Open Source & free alternative to Outlook.com.

    • Proton Mail is Freemium and Open SourceOutlook.com is Freemium and Proprietary
    • Proton Mail is Privacy focusedOutlook.com is not according to our users
  2. Tuta Mail icon

    Tuta Mail

     516 likes
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    Offers comprehensive encryption for email, calendar, and contacts with zero personal info required. Built on open source, install via Play Store, F-Droid, or APK, with Tor and VPN support. Both free and paid plans; utilizes quantum-resistant encryption ensuring privacy-focused, anonymous usage.

    103 Tuta Mail alternatives

    Cost / License

    • Freemium (Subscription)
    • Open Source

    Application types

    Platforms

    • Mac
    • Windows
    • Linux
    • Online
    • Android
    • iPhone
    • iPad
    • Flathub
    • F-Droid
    Tuta Mail screenshot 1
     
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    20
  4. Disroot icon

    Disroot

     113 likes
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    Disroot is a platform providing online services based on principles of freedom, privacy, federation and decentralization.

    44 Disroot alternatives

    Cost / License

    • Free
    • Open Source

    Application type

    Platforms

    • Online
    • F-Droid
    Disroot screenshot 1
     
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    1
    Comments about Disroot as an Alternative to Outlook.com
    lancelotjensen
    Positive
    0

    Great free Email provider with focus on security and privacy. Very happy I switched from Outlook to Disroot!

    Outlook.com Icon
    Disroot icon
    • Disroot is Free and Open SourceOutlook.com is Freemium and Proprietary
    • Disroot is Privacy focusedOutlook.com is not according to our users
  5. Ad
    Screenshot
    Proton Mail icon
    Proton Mail

    Proton Mail provides secure email services with end-to-end encryption, ensuring data protection. Swiss-based and outside US jurisdiction, it offers a free version to champion privacy as a human right. Fully accessible on any devi...

    https://proton.me
    Learn More
  6. Posteo icon

    Posteo

     83 likes
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    Web- and IMAP-based email service. 2GB cost 1€/month. Information is hosted on encrypted hard drives. Electricity from renewable resources is used.

    74 Posteo alternatives

    Cost / License

    • Subscription
    • Open Source

    Application types

    Platforms

    • Online
    Drag and drop
     

    • Posteo is the most popular commercial alternative to Outlook.com.

    • Posteo is Paid and Open SourceOutlook.com is Freemium and Proprietary
    • Posteo is Privacy focused and Security-focusedOutlook.com is not according to our users
  7. Infomaniak kMail icon

    Infomaniak kMail

     38 likes
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    Privacy-focused Swiss email system provides 20 GB free storage, supports custom domains and unlimited storage, syncs contacts and calendars, is ad-free, and is part of a secure productivity suite used by over a million users across Europe on all devices.

    42 Infomaniak kMail alternatives

    Cost / License

    • Freemium (Subscription)
    • Open Source

    Application types

    Platforms

    • Online
    • Android
    • iPhone
    • Android Tablet
    • iPad
    • F-Droid
    Infomaniak kMail screenshot 1
     
  8. Wino Mail icon

    Wino Mail

     8 likes
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    Wino is a lightweight native mail client for Windows 10/11. It is still in active development. Main motivation for this project is to replace Mail & Calendar for Windows with modern Windows design without using web technologies for speed.

    Cost / License

    • Freemium (Pay once)
    • Open Source

    Application type

    Platforms

    • Windows
    Wino Mail screenshot 1
     
  10. Forward Email icon

    Forward Email

     6 likes
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    Forward Email is the best email service, encrypted email service, and fastest email service. It supports unlimited domains and aliases for no extra cost. It uses quantum safe ChaCha20-Poly1305 encryption and offers SMTP, IMAP, POP3, email webhooks, email regular expressions...

    Cost / License

    • Freemium (Subscription)
    • Open Source

    Application type

    Platforms

    • Self-Hosted
    • Online
    Forward Email screenshot 1
     

    • Forward Email is the most popular Self-Hosted alternative to Outlook.com.

    • Forward Email is Freemium and Open SourceOutlook.com is Freemium and Proprietary
    • Forward Email is Privacy focusedOutlook.com is not according to our users
  11. Onion Mail icon

    Onion Mail

     4 likes
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    The power of simplicity. Onion Mail can manage emails in the normal network and in the Tor. Onion Mail protect your privacy and anonymity.

    31 Onion Mail alternatives

    Cost / License

    • Freemium
    • Open Source

    Application types

    Platforms

    • Online
    • Android
     
  12. Zero Email icon

    Zero Email

     4 likes
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    Zero is an open-source AI email solution that gives users the power to self-host their own email app while also integrating external services like Gmail and other email providers. Our goal is to modernize and improve emails through AI agents to truly modernize emails.

    Cost / License

    • Free
    • Open Source

    Application type

    Platforms

    • Online
    • Self-Hosted
    • Docker
    Zero Email screenshot 1
     
  13. EGroupware icon

    EGroupware

     9 likes
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    Web-based team collaboration suite combining email client, calendar, contact and task tools, CRM, project and file management, file sharing, trouble tickets, Rocket.Chat chat, and Collabora online editing. Offers open source, self-hosted, and SaaS options.

    23 EGroupware alternatives

    Cost / License

    • Freemium (Subscription)
    • Open Source

    Application types

    Platforms

    • Linux
    • Online
    • Self-Hosted
    • Software as a Service (SaaS)
    EGroupware on the desktop --- EGroupware offers with the modules - E-mail - Calendar - Address book - InfoLog (tasks, notes, ...) - File manager - Ticket system - Project Manager - Timesheet - Collabora Online Office - Rocket.Chat an entire office in the browser.
     
  14. Galae icon

    Galae

     Like
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    Galae is a secure email service focused on deliverability, self-management and interoperability. It totally relies on free/libre opensource software.

    Cost / License

    • Subscription
    • Open Source

    Application type

    Platforms

    • Online
    • Software as a Service (SaaS)
     
  15. Columba icon

    Columba

     6 likes
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    Columba is an email client written in Java, featuring a user-friendly graphical interface with wizards and internalionalization support. Its a powerful mail management tool with features to enhance your productivity and communication.

    Cost / License

    • Free
    • Open Source

    Application type

    Alerts

    • Discontinued

    Platforms

    • Mac
    • Windows
    • Linux
    • BSD
    Columba screenshot 1
     
12 of 16 Outlook.com alternatives