← Back to the overview

Open source, Apache 2.0

By Lucas Flores, IT Systeme Flores UG. Last updated 2026-10-16

Restow is one repository and one release in two builds. Everything outside the ee/ directory, the core, is open source under the Apache License 2.0. The Business and Service Provider modules live in ee/ and are licensed under the Restow license terms: the code is visible, and using the modules in production needs a valid license key.

The Community edition is the core: free of charge for one organization, with no mailbox limit and no license key at all. Every release comes in two builds of the same commit. The full images, restow and restow-web, carry the core and the modules; the Community images, restow-community and restow-web-community, carry the core only, with no code from ee/ at all. Both use the same database, so switching means changing the two image lines and running docker compose up -d.

What's public today

The complete source code, including the ee/ directory, is public on GitHub, where every release is published. Version 0.1.0, the first public release, is out now as a beta: test it before you rely on it, and keep an independent backup alongside it while it is new. Known limits: the release checks have not yet been run against a real Microsoft 365 tenant (Microsoft 365 backup and restore are covered by tests against a simulated Graph API), and the endpoint agent's install script was run in the release checks only in a Linux container; the macOS installer was not part of them. See how Restow is built for the full account of the development process this code goes through.

One repository, two licenses

There is no separate closed-source product. The core is under the Apache License 2.0, the code in ee/ under the Restow license terms. In the full images without a key, the Business and Service Provider features stay locked: a locked menu entry stays visible, greyed out, and leads to the license section (Admin › License), where the key is installed, with no banners or pop-ups. The Community images have no such entries and no license settings at all.

What the paid editions actually add (and don't)

Business and Service Provider unlock what lives in ee/: legal holds (per tenant or per mailbox), the SMTP journal receiver for Exchange Online, archive deletion runs (enforced retention), the audit log viewer (search, filter, details, chain verification) and its export (CSV, JSON with hashes), and scheduled summary reports. Service Provider adds the cross-tenant provider API, the provider view of the Overview (tenant matrix, alerts), the "All tenants" view of the Jobs and limiting a team member to chosen tenants. Continuous archive capture from the mailboxes (Microsoft Graph and IMAP sync, since 0.4.4) is a license capability in the same way: the Community build keeps the capture service idle. All of it is present in the full images, and the license key decides at runtime which of it is active; the Community images do not contain it. Not everything around these features is finished: sign-in with Microsoft and single sign-on (SSO) are planned, and so is white label for Service Providers; four-eyes approval and a signed restore proof are planned too, see the roadmap.

Deliberately in the core, in every edition: the team with roles (several administrators, since 0.3.1), the archive export (EML in a ZIP, or MBOX, readable without Restow), the database schema, the settings for archive retention and the recording of the audit log. Every read and every restore is written to the append-only, hash-chained audit log in every edition; only viewing, filtering and verifying it is Business and Service Provider. Since 0.4.0 backing up file shares, immutable backups and ransomware detection are in the core too, in every edition.

The license key is a fair-play mechanism, not DRM: it is verified offline against a signed Ed25519 key, does not phone home, does not expire your access to a version you already have, and never limits restore. Restore is never limited by edition, in any version. See pricing for exact terms. If development ever stops, the project has committed to announce it at least twelve months in advance and then publish ee/ as open source under the core's license, Apache 2.0; installations keep running without a key.

Contributing

How to contribute, and what a contribution needs, is described in CONTRIBUTING.md in the repository.

Getting your data back without Restow at all

Open source extends past the application code to the data itself: the chunk-store format is open and documented, and a small standalone tool restores from it even with no Restow server running, so open source here also means you can get your own backup back even in the worst case, not just read the code. See exit costs and vendor lock-in for why that specific property is worth having in writing.

Frequently asked

View the repository on GitHub →