Open-source alternatives guide · Updated 2026
Compare the best free and open-source alternatives to Microsoft 365 — 6 verified projects with explicit catalog relationships. Inspect licenses, GitHub activity, self-hosting signals, and migration fit before you switch.
Official product reference Microsoft 365↗Only explicit alternative relationships are shown—never inferred competitor claims.
This guide compares 6 verified open-source alternatives to Microsoft 365, including CryptPad, Tuta, ONLYOFFICE, and Papra.
Projects appear across Productivity, Security & Privacy, and Infrastructure. 1 option includes a self-hosting signal — see the self-hosted catalog. Ranking follows public GitHub stars and recorded momentum—not vendor marketing. Compare projects side by side, then confirm license fit, migration effort, and operational ownership before adopting any option.
Strongest repository-activity signal: CryptPad · Jump to ranking · 7.8K stars
Proprietary productivity suite from Microsoft.
Visit Microsoft 365Compare capabilities, licensing, and ownership model. Stars help with discovery; they are not a security or product-fit guarantee.
Collaborative office suite, end-to-end encrypted and open-source.
Collaborative office suite, end-to-end encrypted and open-source. Review the official repository, license, release activity, and deployment documentation before production adoption
Open-source alternative to Microsoft 365
Tuta is an email service with a strong focus on security and privacy that lets you encrypt emails, contacts and calendar entries on all your devices.
Tuta is an email service with a strong focus on security and privacy that lets you encrypt emails, contacts and calendar entries on all your devices. Review the official repository
ONLYOFFICE Docs is a free collaborative online office suite comprising viewers and editors for texts, spreadsheets and presentations, forms and PDF, fully compatible with Office Open XML formats: .docx, .xlsx, .pptx and
ONLYOFFICE Docs is a free collaborative online office suite comprising viewers and editors for texts, spreadsheets and presentations, forms and PDF, fully compatible with Office Op
Open-source alternative to Microsoft 365
The minimalistic document archiving platform.
The minimalistic document archiving platform. Review the official repository, license, release activity, and deployment documentation before production adoption.
Read-only LibreOffice core repo - no pull request (use gerrit instead https://gerrit.libreoffice.org/) - don't download zip, use https://dev-www.libreoffice.org/bundles/ instead
Read-only LibreOffice core repo - no pull request (use gerrit instead https://gerrit.libreoffice.org/) - don't download zip, use https://dev-www.libreoffice.org/bundles/ instead R
Open-source alternative to Microsoft 365
Issue tracker only. Active development is on Gerrit at https://gerrit.collaboraoffice.com/.
Issue tracker only. Active development is on Gerrit at https://gerrit.collaboraoffice.com/. Review the official repository, license, release activity, and deployment documentation
Map must-have capabilitiesList the workflows in Microsoft 365 you cannot drop during migration.
Verify the licenseConfirm it fits your use, distribution, and compliance model. Browse license briefs.
Run a proof of conceptTest real data, integrations, clients, and failure modes. Use Compare for side-by-side checks.
Plan ownershipAssess upgrades, backups, support, and an exit path. Read when self-hosting is worth it.
OpenSourceChoice currently lists 6 projects with an explicit alternative relationship to Microsoft 365. Catalog highlights include CryptPad, Tuta, and ONLYOFFICE. Rankings follow public GitHub stars and recorded momentum—not paid placement. Match capabilities and license fit to your workflow before adopting any option.
Most catalogued alternatives publish source under OSI or source-available licenses and are free to inspect. Hosting, commercial support, or cloud model APIs may still cost money. Always read the project license for your use case.
1 option in this list carry a self-hosting signal. Confirm the official install guide, backups, upgrades, and hardening steps before production.
Map must-have Microsoft 365 workflows, verify license and compliance fit, run a proof of concept with real data and integrations, then plan ownership for upgrades, backups, support, and an exit path.
Narrow the same alternatives by search, license, tags, or self-hosting signals when you need a tighter shortlist.
Collaborative office suite, end-to-end encrypted and open-source.
ProductivityOpen-source projects grouped in this category for discovery and comparison.#
JavaScriptProjects tagged with this topic in the verified catalog.
Github ActionsProjects tagged with this topic in the verified catalog.
NodeJSProjects tagged with this topic in the verified catalog.
Microsoft 365Proprietary productivity suite from Microsoft.Tuta is an email service with a strong focus on security and privacy that lets you encrypt emails, contacts and calendar entries on all your devices.
Security & PrivacyOpen-source projects grouped in this category for discovery and comparison.#
TypeScriptProjects tagged with this topic in the verified catalog.Github ActionsProjects tagged with this topic in the verified catalog.JavaScriptProjects tagged with this topic in the verified catalog.Microsoft 365Proprietary productivity suite from Microsoft.
LatviaAGPL-3.0ONLYOFFICE Docs is a free collaborative online office suite comprising viewers and editors for texts, spreadsheets and presentations, forms and PDF, fully compatible with Office Open XML formats: .docx, .xlsx, .pptx and
ProductivityOpen-source projects grouped in this category for discovery and comparison.#
ShellProjects tagged with this topic in the verified catalog.Github ActionsProjects tagged with this topic in the verified catalog.BashProjects tagged with this topic in the verified catalog.Microsoft 365Proprietary productivity suite from Microsoft.The minimalistic document archiving platform.
InfrastructureOpen-source projects grouped in this category for discovery and comparison.#TypeScriptProjects tagged with this topic in the verified catalog.Github ActionsProjects tagged with this topic in the verified catalog.JavaScriptProjects tagged with this topic in the verified catalog.Self-hostedThis project carries a self-hosting or local-deployment signal. Verify the official install guide before production use.Microsoft 365Proprietary productivity suite from Microsoft.
GermanyGPL-3.0Read-only LibreOffice core repo - no pull request (use gerrit instead https://gerrit.libreoffice.org/) - don't download zip, use https://dev-www.libreoffice.org/bundles/ instead
Content & CollaborationOpen-source projects grouped in this category for discovery and comparison.#
C++Projects tagged with this topic in the verified catalog.Github ActionsProjects tagged with this topic in the verified catalog.JavaScriptProjects tagged with this topic in the verified catalog.Microsoft 365Proprietary productivity suite from Microsoft.
United KingdomLicense not declaredIssue tracker only. Active development is on Gerrit at https://gerrit.collaboraoffice.com/.
InfrastructureOpen-source projects grouped in this category for discovery and comparison.#ShellProjects tagged with this topic in the verified catalog.Github ActionsProjects tagged with this topic in the verified catalog.JavaScriptProjects tagged with this topic in the verified catalog.Microsoft 365Proprietary productivity suite from Microsoft.
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