Download
Every Herkos app, for every system it runs on. One key signs you in to all of them.
Herkos Mail already works in the browser, at app.herkos.app. The installers for Android, Windows and Linux will download from the buttons below as soon as the first version is published, with checksums; until then those buttons are greyed out. We would rather show an empty button than one that installs something untested.
Herkos Mail
Private mail between Nostr users, end-to-end encrypted, and ordinary email through a bridge.
In the browser your key lives in the browser: sign in there with a remote signer, or read the security page first.
Herkos Calendar Coming soon
A private agenda where every event is encrypted before it reaches a relay.
Not available yet. It will appear here, for the same systems, as soon as it is ready — and it will sign in with the same key as Herkos Mail.
Herkos Notes Coming soon
Private notes in Markdown, encrypted to your key before they reach a relay.
Not available yet. It will appear here, for the same systems, as soon as it is ready — and it will sign in with the same key as Herkos Mail.
Herkos Drive Coming soon
Encrypted files on Blossom servers, replicated so no single operator can lose them.
Not available yet. It will appear here, for the same systems, as soon as it is ready — and it will sign in with the same key as Herkos Mail.
Herkos Bunker Coming soon
A NIP-46 signer that keeps your key and signs for the other Herkos apps.
Not available yet. It will appear here, for the same systems, as soon as it is ready — and it will sign in with the same key as Herkos Mail.
Android from F-Droid
Herkos publishes its own F-Droid repository, so the F-Droid app installs updates for you. In F-Droid open Settings → Repositories, tap + and add this address (the fingerprint at the end lets F-Droid check that the repository is really ours):
https://fdroid.herkos.app/fdroid/repo?fingerprint=74AAD1BBC696DE1A738BDCDCDEC5911347DB198C7253347FA187FC40D79636B3The Android build has no Google services in it and uses UnifiedPush for notifications.
Windows: why it warns you, and when it will not run
Herkos for Windows is not code-signed. A signing certificate for an individual publishes the developer's legal name, and the Microsoft Store is not an option for us either, so we sign nothing and publish checksums instead (below). Windows reacts to that in one of two ways:
- SmartScreen (most PCs): a blue window, “Windows protected your
PC”. Click More info, check that it names
Herkos.exe, then Run anyway. It asks once per version. - Smart App Control (turned on by default on some new Windows 11 installations): it blocks the app outright, with no “Run anyway” button. Microsoft allows no exception for a single app; the only way through is to turn Smart App Control off (Windows Security → App & browser control → Smart App Control settings), which lowers the protection for every app on that PC. Since the April 2026 update it can be turned back on without reinstalling Windows. If you would rather not touch it, use the web version or a phone for now.
Check what you downloaded
Every release comes with a SHA256SUMS file on the
Releases page, and the same sums will be listed on this page.
They are published in two places on purpose: to fool you, someone would have to tamper with
both. Compare before you open anything:
# Windows (PowerShell)
Get-FileHash .\herkos-*-windows-x64-portable.zip -Algorithm SHA256
# Linux and macOS
sha256sum -c SHA256SUMS --ignore-missingIf the result does not match, delete the file and tell us at hello@herkos.email. The Android APK is also signed with our key, so Android itself refuses an update that does not come from us.
macOS and iOS
They come later, once the signing and notarisation side is in place. Until then, use the browser version on a Mac or an iPhone.