Submarine is a free, open-source password manager for Windows, built for people who want their logins, cards and secure notes synced across devices without creating an account. Everything is encrypted before it leaves your device, then stored on Nostr relays, which are open servers anyone can run and which only ever handle encrypted data.
It suits privacy-minded users who prefer not to rely on a single company's cloud, and anyone moving over from Bitwarden, since existing vaults can be imported. The project is at version 0.2.0, so it is still early in its life. Treat it as a promising option for everyday accounts and keep your most critical credentials backed up somewhere else until you are comfortable with it.
What Submarine Is and Who It Suits
Submarine is a password manager first and foremost. Its job is to hold the credentials you use every day, including logins, payment cards, two-factor codes and private notes, and to keep them consistent across the devices you own. It is not a social network app, and it does not try to be one.
The people who get the most from it tend to share a few traits. They want their vault to be open source, they dislike the idea of a single provider holding every secret, and they are comfortable reading a changelog before updating. Developers who like to inspect how their tools work will also find the public code useful.
If you mostly need a password manager for a handful of accounts, the feature set covers the basics without extras. If you run a large household or team with complex sharing rules, check the features against your needs before committing, since the project is still at an early version.
How Encrypted Vaults Travel Over Nostr Relays
Nostr relays are simple servers that accept and return messages. Anyone can run one, and a person can connect to several at once so that the loss of one relay does not stop the others from holding a copy. Submarine uses this model to store your vault, which means the storage layer is spread across independent operators instead of one company's cloud.
Because encryption happens on your device, relays only handle ciphertext. A relay operator can see that data is being stored and roughly how much, but not the contents of your logins. That distinction is the core of the design, and it is why the app can sync without asking you to trust the relay with readable passwords.
The trade-off is availability. If the relays you depend on are slow or offline, updates wait on your device until a connection is possible. Your local copy remains usable in the meantime, so day-to-day work is not blocked, but other devices will not see your latest edits until the relays catch up.
Everyday Scenarios for a Synced Password Vault
Consider a common setup: a Windows desktop at home, a laptop for travel and a phone for quick logins. With a single vault synced across all three, you can create a new account on the laptop and find the password on the desktop an hour later without copying files by hand.
Another scenario involves switching from Bitwarden. You can import your existing vault, check that the entries look right, and keep the old manager running until you are satisfied. If the new setup is not for you, the export function lets you move the data back at any time.
Finally, separate vaults help keep work and personal credentials distinct. A contractor who uses several client systems can keep those logins in their own vault, opened only on the machines that need them, while family accounts stay in a different one.
Key features
Logins, cards and secure notes
Two-factor codes beside your logins
Password, passphrase and username generator
Import from Bitwarden and export back
Several vaults side by side
Changes saved on the device first
Lock password with biometric shortcut
Clipboard cleared after a delay
Screenshot blocking and hidden recent apps
Command-line client
Interface in ten languages
Supported coins
Submarine's storage runs on the Nostr network, which is the only network the project lists. Your vault is encrypted on your device before anything reaches Nostr relays, so the relays handle encrypted data rather than readable entries. The app is a password manager and does not manage cryptocurrency coins.
How to install Submarine on Windows
- 1
Get the Windows build
Open the project's GitHub Releases page and download the Windows build from the latest release, currently v0.2.0. Download only from the official source, meaning that page, and avoid copies offered on file-sharing or mirror sites.
- 2
Verify the file
Calculate the SHA-256 hash of the downloaded file with a tool such as PowerShell's Get-FileHash, then compare the result with the checksum published on the release page. If the release also includes a signature, check that as well. If any value does not match, delete the file and download it again.
- 3
Install the app
Run the installer or extract the Windows build into a folder you control, then launch Submarine from there. Only the ready-made program is needed for everyday use, so you do not have to install developer tools to run it.
-
Set up your lock and first vault
On first launch, choose a lock password, enable your fingerprint, face or screen lock if your device supports it, and create your first vault. If you already use Bitwarden, import the export file at this stage so your logins are ready on day one.
How to use Submarine
Once installed, most of the work happens in a few short steps. Start with one vault and add your most important accounts first, then expand from there as you get comfortable with the app.
- Create your lock password and turn on biometric unlock if your device supports it.
- Create a vault, or import your Bitwarden export to bring in existing logins.
- Add an entry for each account, using the generator for every new password you create.
- Attach two-factor codes to the logins that offer them, so sign-ins stay in one place.
- Copy a password when you need it. It is cleared from the clipboard after a short delay.
- Open the same vault on your other devices and confirm that a recent change has reached them.
- Export a copy to Bitwarden format whenever you want a backup outside Submarine.
Pros & cons
- Everything is encrypted before it leaves your device.
- No account is needed to start using the app.
- Free and open source, with no ads and no tracking.
- Existing Bitwarden vaults can be imported, and exported back at any time.
- Edits are saved locally first, so you can keep working without a connection.
- Interface available in ten languages, including English, German and Japanese.
- Syncing depends on Nostr relays being reachable, so other devices can lag behind.
- The project is at version 0.2.0, so it has a shorter release history than long-established managers.
- Relays are run by independent operators, so their uptime and policies are outside your control.
- Power users who want a deep set of sharing or team features should check whether the current feature set meets their needs.
Is Submarine safe?
Submarine stores your passwords, so treat its download and setup as security-sensitive. Download only from the official source, which is the project's GitHub Releases page, and verify the SHA-256 checksum or signature before running the file. Never enter your Nostr keys, lock password or any recovery phrase on third-party websites, including sites that offer to sync or import your vault for you.
The code is MIT licensed and public, so it can be reviewed by anyone with the skills to do so. Check the latest version on the official website before you update, and read the release notes first. Store your lock password somewhere you trust, and do not share it with anyone.
- Official source only. Download from github.com/nogringo/submarine. Ignore ads and lookalike domains.
- Check the SHA-256. Compare the installer hash with the value the developer publishes before running it.
- Never share your seed phrase. No developer, support agent or website — including CryptApps — will ever ask for it.
Alternatives
Most programs in this Nostr category are social or messaging clients, such as Amethyst, Gossip and Coop, or command-line tools like NAK and Nostr Commander RS. They help you read, post and message on Nostr, which is a different job from storing secrets. Nostr VPN and Blockcore Notes also draw on the wider Nostr ecosystem, but they serve networking and social organization rather than password storage.
Submarine uses Nostr relays only as encrypted storage. It is not a feed, a chat app or a note-taking tool. If you want a password vault that syncs through open relays, it is the option on this list built for that purpose. If you want to browse or publish on Nostr, a client from the list is the better starting point.
Specifications
- Price
- Free
- Type
- Open source
- License
- MIT
- Latest version
- v0.2.0
- Last update
- 29 Oct 2026
- Windows support
- Yes (Windows build or installer)
- Source code
- github.com/nogringo/submarine
Frequently asked questions
Yes. Submarine is free and open source under the MIT license, with no ads and no tracking. You do not pay to create a vault or to sync it across devices, and because the code is public, anyone can read how it works or build their own copy.
It is designed to be, because everything is encrypted before it leaves your device and relays only ever handle encrypted data. Your own habits still matter, so choose a strong lock password, verify the download before installing, and never enter your Nostr keys on third-party sites.
No. Submarine does not require an account, so you can start a vault on your Windows PC without signing up for a service. The vault syncs through Nostr relays, and you can open it on as many devices as you like once it is set up on each one.
Yes. Submarine can import from Bitwarden, and it can export back to Bitwarden whenever you need to. This lets you try the app with your existing logins without retyping them, and it keeps your options open if your needs change later on.
The change is saved on your device first. Submarine sends it to the Nostr relays once they are reachable again, so editing does not stop when your connection drops. Until the update reaches the relays, your other devices will continue to show the older version.
Yes. You can keep two-factor codes next to the login they protect, so you can copy a code without switching apps. The codes sit in the same encrypted vault as your passwords, which keeps your sign-in details together and protected by the same lock.
No. Submarine is a password manager that uses Nostr relays as encrypted storage. It does not show a feed or let you publish posts. If you want a Nostr client for social use, the similar programs listed on this page are a better fit for that purpose.
Yes. Submarine includes a command-line client that works in a similar way to the Bitwarden CLI, so you can read and manage your vault from a terminal. It suits people who script routine tasks or prefer keyboard-driven work, and it is a natural step if you already automate Bitwarden.
Verdict
Submarine suits people who want a free, open-source password manager with encrypted sync and no account to create. It is a good match for privacy-minded Windows users who like the idea of storage spread across open relays, and for anyone moving over from Bitwarden. If you need a long track record or a fully mature ecosystem, weigh the early version number before trusting it with every credential you own. Check the latest version on the official website before you install.