Nostr client and relay is a free, open-source toolkit for people who want to work with the Nostr protocol from Windows, Linux or the command line. It is built as a C++ engine, so developers can assemble their own Nostr applications, while technically minded users can run the ready-made components directly. If you want a decentralized social client or your own relay and you are comfortable with terminal tools, this is the project to look at.
The package bundles a command-line client, a command-line relay, a native desktop client and a web interface, all built on the same engine. One caveat up front: the native mobile client, Mostro, is deprecated, so do not plan around it. The codebase was last updated in November 2025, which means the desktop and command-line parts have been recently updated.
What Is a Nostr C++ Engine?
A Nostr C++ engine is a set of reusable code that handles the core tasks of the protocol, such as creating signed events, connecting to relays and reading their replies. Instead of writing that logic from scratch, a developer can build on top of it and focus on the interface or the features that make an application unique.
This project takes that idea further than a single library. The same engine powers a terminal client, a relay, a desktop client and a web interface. That shared core means behavior stays consistent across the components, which helps when you are testing how an app should handle messages.
For ordinary users, the engine matters less than the finished programs built on it. You do not need to compile anything to use the ready-made tools, but knowing that they share one base explains why the set feels like a family of related applications rather than four unrelated products.
Who Is This Software For?
The clearest audience is developers who want to build Nostr applications in C++ and need a working base. A small team could use the engine to prototype a desktop client, then add a web front end using the same underlying code.
Technically comfortable users form a second group. If you already work in a terminal, the command-line client and relay can feel natural, and they are easy to combine with scripts. Someone who wants to automate posting or monitor a relay will find the command-line tools more useful than a graphical app.
Privacy-minded readers may also be interested in running a relay of their own. A private relay gives you a place to test messages without depending on a public server, although it only helps if the clients you use are configured to connect to it.
How Clients and Relays Work Together
In Nostr, clients and relays play separate roles. A client creates and signs notes with a user's key pair, then sends them to one or more relays. A relay receives those notes, stores them and passes them on to clients that ask for them. Because a user can choose which relays to use, no single server has to hold the whole network.
That design explains why this project includes both sides. You can run the client to publish and read notes, and run the relay to store and serve them. Testing both ends on one machine lets you see how a message moves from creation to delivery.
A practical example: you publish a test note with the command-line client to your own relay, then open the desktop client and connect it to the same relay address. If the note appears in both places, the chain is working. If it does not, check the relay address and connection settings first.
Why a Command-Line Foundation Still Matters
Command-line tools may look old-fashioned, but they have clear advantages for certain jobs. They are easy to script, easy to run on a server without a desktop environment, and simple to repeat with the same settings each time. For a developer, that predictability is valuable when debugging.
The project's graphical programs are built on the same foundation, so the terminal tools serve as a useful reference. If something works in Nostro, it gives a clear point of comparison when you suspect a bug in Gnostro. That is a practical habit for anyone building software on top of a protocol.
The trade-off is a steeper learning curve. Newcomers may need time to get comfortable with terminal commands and key handling before the tools feel easy. A few short sessions practicing on a test relay usually pay off quickly.
Key features
Command-Line Client (Nostro)
Command-Line Relay (Vostro)
Native Desktop Client (Gnostro)
Web Interface (Wostro)
Mobile Client (Mostro, Deprecated)
Supported coins
The documentation refers to Nostr as the network the software works with. Nostr is a protocol rather than a blockchain or a cryptocurrency, so there is no coin list to check. The client and relay components follow the same protocol, so the practical question is which relays you connect to.
How to install Nostr client and relay on Windows
- 1
Open the official project page
Go to the project's GitHub repository at https://github.com/pedro-vicente/nostr_client_relay and open the Releases section. Download only from the official website or the project's GitHub Releases page, and avoid copies offered by other sites.
- 2
Look for a Windows build
Check the release list for a file labeled for Windows. The project lists Windows support as likely, so if no prebuilt Windows file appears, the software is intended to be built from source, which is a developer task rather than a standard installation.
- 3
Verify the download
Compare the file's SHA-256 checksum with the value published on the release page, or check the signature if one is provided. You can compute the hash with the Get-FileHash command in PowerShell. Do not run a file whose hash does not match.
-
Install and launch
If the release is an archive, extract it to a folder you can find again, such as Documents or a dedicated tools folder. If it includes an installer, run it. Start the component you need from its executable, or open a terminal in that folder and run it from there.
How to use Nostr client and relay
Once the components are installed, the easiest start is to pick one component and run it with default settings. The steps below assume you are using a Windows PC with the desktop client or the command-line tools.
- Open a terminal in the folder where you extracted the files, or double-click the desktop client's executable.
- Start the command-line client first for a quick test. Check the help output or the repository's documentation to see the available commands.
- Add the relays you want to connect to. Public relays are the simplest choice for trying things out.
- Create or import your Nostr key pair. Store the private key somewhere safe, and never paste it into a website you do not trust.
- Publish a short test note, then check that it appears in the client view and on the relay you chose.
- If you want your own relay, start Vostro and point a client to its address, so you can compare how it behaves against public relays.
- Stop the tool when you are finished, and note the commands you used so you can repeat the same setup later.
Pros & cons
- Free and open source, with the source code publicly available on GitHub
- Covers command-line, relay, desktop and web use in one codebase
- Command-line tools are scriptable and easy to automate
- Lets you run your own relay for testing or private use
- Desktop client is listed with builds for Mac, Linux and Windows
- The mobile client Mostro is deprecated
- Windows support is described as likely, so a ready-made Windows package may not always be available
- Command-line tools have a learning curve for less technical users
- Less suited to people who want a polished, one-click experience
Is Nostr client and relay safe?
Start with the source: download only from the official website or the project's GitHub Releases page, and compare the file's SHA-256 checksum with the value published there before running it. Windows antivirus tools sometimes flag new or unsigned executables, and that can happen with legitimate software too. If a warning appears, verify the hash rather than turning protection off entirely.
Nostr keys deserve particular care. Your private key controls your identity, so never paste it into third-party websites, browser extensions or chat messages. The mobile client Mostro is deprecated and should not be treated as supported. The project was last updated in November 2025, but check the latest version on the official website before installing.
- Official source only. Download from github.com/pedro-vicente/nostr_client_relay. 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
Several similar programs focus on one job. Gossip and Vega are desktop clients, Nostr Commander RS and NAK work from the command line, and Amethyst is a Nostr client in its own right. Nostr client and relay differs because it puts a command-line client, a relay, a desktop client and a web interface in one C++ codebase.
If you want to run your own relay alongside a client, this project covers both sides. If you only want a polished daily driver for posting and reading, a dedicated client such as Gossip or Vega is usually the simpler starting point.
Specifications
- Price
- Free
- Type
- Open source
- License
- —
- Latest version
- —
- Last update
- 4 Nov 2025
- Windows support
- Likely (builds for Windows; check releases)
- Source code
- github.com/pedro-vicente/nostr_client_relay
Frequently asked questions
Yes. The software is free and open source, and its source code is published on GitHub. You can run it without a license fee, but check the project page for any licensing terms before redistributing it. The code is written in C and C++, so developers who want to modify it can build it themselves.
Windows is listed as a likely platform, and the project mentions builds for Windows, including the native desktop client Gnostro. Check the releases page for a current Windows package. If none is listed, the software is intended to be built from source, which is a developer task. The project is also listed for Linux.
The code is open source, which makes it possible for others to inspect it, and the last code update was in November 2025. Safety still depends on where you get the file. Use the official website or GitHub Releases, and verify the SHA-256 checksum before running anything.
A client is the app you use to read and write notes, while a relay is a server that receives, stores and delivers those notes. A single user typically connects a client to several relays. Nostr client and relay bundles both roles, so you can run whichever part fits your needs.
Yes. Vostro is the command-line relay included in the project. Running your own relay lets you test applications locally or keep a relay under your control. Other clients will only see your notes if they connect to your relay, so you need to share its address or configure clients to use it.
No. Mostro, the native mobile client, is listed as deprecated. That means it should not be treated as a current option for daily use. If you need a mobile Nostr app, compare other clients from the alternatives discussed on this page instead of building plans around Mostro.
Verdict
Nostr client and relay suits developers, technically comfortable users and anyone who wants to run their own Nostr relay or build a client. It is free, open source and covers command-line, desktop and web use from one codebase. It is less suitable for people who want a polished mobile app, because Mostro is deprecated. Check the releases page for the latest Windows build before you start, and treat the software as a toolkit rather than a finished consumer product.