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A real desktop in the browser
Both daedalOS and UltimaOS give you a genuine desktop experience in a browser tab — windows, a taskbar, a launcher and apps — with nothing to install locally.
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Comparison
UltimaOS vs daedalOS
Two web desktops, two very different purposes.
daedalOS is a superb open-source desktop environment in the browser — an ambitious, single-developer project that recreates a full windowed OS experience client-side, and a genuine showcase of how far the web platform can go. UltimaOS shares the same core idea — a real desktop that runs in a browser tab — but is built for a different job: a hosted, end-to-end encrypted, EU-sovereign workspace for everyday private work. If you want an open, local, hackable web desktop to explore and build on, daedalOS is excellent. If you want a production workspace where your data is encrypted and lives under EU jurisdiction, that is what UltimaOS is for.
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Overview
What they share.
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The web platform, pushed hard
Both show what the modern browser can do: file systems, multiple apps and a full windowing environment running as web technology rather than native software.
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Open ideas about the OS
Both treat applications as citizens of an operating system with a shared file system, rather than as separate, disconnected products.
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Details
Where they diverge.
The overlap is the desktop metaphor. The difference is what each is built to do — and that changes everything about privacy, storage and jurisdiction.
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Purpose
daedalOS is an open-source project and a technical showcase — a browser desktop you run, explore and build on, largely client-side. UltimaOS is a hosted product built for daily private work, with accounts, cross-device sync and a suite of real applications.
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Where your data lives
daedalOS runs in your browser and stores files locally in the browser's own storage; there is no hosted, encrypted backend behind it. UltimaOS stores your data in an end-to-end encrypted Personal Storage layer on EU infrastructure, syncing across devices while the server holds only ciphertext.
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Encryption and identity
daedalOS is a desktop environment, not an encryption product — it does not set out to provide end-to-end encrypted accounts. UltimaOS is built around encryption: identity bound to your keys, no password database, 3-of-5 social recovery, and NIST post-quantum algorithms at the OS layer.
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Sovereignty
Because UltimaOS is an EU entity hosting on EU infrastructure under EU jurisdiction, sovereignty is part of the product. daedalOS, as a client-side project, simply is not making that claim — it is a different kind of thing.
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Key points
Which one is for you.
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Choose daedalOS to explore and build
If you want an open-source, hackable web desktop to learn from, tinker with or extend, daedalOS is a genuinely impressive place to do it.
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Choose UltimaOS for private daily work
If you want mail, files, documents, chat and calendar as a real workspace — encrypted end-to-end and hosted in the EU — that is what UltimaOS is built for.
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They are not really competitors
One is an open showcase of the web desktop; the other is a private, production workspace. The honest comparison is of purpose, not a scoreboard.
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References
Standards and references.
- daedalOS — source (GitHub) ↗ github.com
- NIST FIPS 203 — ML-KEM standard ↗ csrc.nist.gov
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Frequently asked
UltimaOS vs daedalOS — common questions
Is UltimaOS like daedalOS?
Short answer
They share the idea of a real desktop running in the browser, but they are built for different things. daedalOS is an open-source, largely client-side web desktop and technical showcase; UltimaOS is a hosted, end-to-end encrypted, EU-sovereign workspace for everyday private work.
Is daedalOS encrypted?
Short answer
daedalOS is a browser desktop environment rather than an encryption product; it stores files in the browser's own local storage and does not set out to provide end-to-end encrypted hosted accounts. UltimaOS encrypts your data end-to-end and stores only ciphertext on EU infrastructure.
Is daedalOS open source?
Short answer
Yes — daedalOS is an open-source project, and a genuinely impressive one. UltimaOS is a different category: a hosted product built around encryption, accounts and EU-hosted storage.
Where does each store my files?
Short answer
daedalOS stores files locally in your browser. UltimaOS stores them in an end-to-end encrypted Personal Storage layer on EU infrastructure, synced across your devices, with the server holding only ciphertext.
Which should I use?
Short answer
Use daedalOS to explore and build on an open web desktop. Use UltimaOS if you want a private, encrypted, EU-hosted workspace for real daily work — mail, files, documents, chat and more.