Webassembly client

The Nym webassembly client allows any webassembly-capable runtime to build and send Sphinx packets to the Nym network.

You can install @nymproject/nym-client-wasm from NPM from its package page, or

npm i @nymproject/nym-client-wasm

The nym-client-wasm package allows easy creation of Sphinx packets from within mobile apps and browser-based client-side apps (including Electron or similar). Browser extensions should also work.

As the quickstart example shows, it’s possible to deliver web apps that build and send Sphinx packets in a solely in a web browser window. However, note that all the normal constraints of browser-based key storage and same-origin rules (which are there for good reason) make it difficult to structure pure webapps apps securely. We are still assessing what can be done here, if anything.

Building peaps with nym-client-wasm

We’ve already looked that the basics of peap creation via the webassembly client in the quickstart.

Initializing a new Nym identity

The main methods you’ll use from the NPM package are:

let identity = new Identity();

This generates a new Nym identity, consisting of a public/private keypair and a Nym gateway address.

Constructing a Nym client

let client = new Client(directoryUrl, identity, authToken);

This returns a nym Client which connects to a Nym gateway via websocket. All communication with the Nym network happens through this client.

The directoryUrl of the Nym testnet is https://directory.nymtech.net. Use that if you want to connect to the running testnet.

If you are running a local network, use as your directoryUrl.

Running the Nym client


This will cause the client to retrieve a network topology from the defined directoryUrl, and connect to its gateway via websocket. Cover traffic is not yet sent, but message sends should work after client start.

Sending messages

client.sendMessage(message, recipient) {

Sends a message up the websocket to this client’s Nym gateway.

NOTE: the webassembly client currently does not implement chunking. Messages over ~1KB will cause a panic. This will be fixed in a future version.

message must be a string at the moment. Binary Blob and ArrayBuffer will be supported soon.

recipient is a Nym address as a string.

Getting the client’s address

Given a client, to get its address, you can call:



Anonymous replies using surbs don’t yet work in the webassembly client. They should be available in the next release (0.8.0).


Sending JSON is fairly simple. If you’re playing with the quickstart wasm example app, just stick it into the message box and send it (or send it programmatically as the message content of client.sendMessage(message, recipient) in your own application code.

Think about what you’re sending!

Think about what information your app sends. That goes for whatever you put into your Sphinx packet messages as well as what your app’s environment may leak.

Whenever you write client peaps using HTML/JavaScript, we recommend that you do not load external resources from CDNs. Webapp developers do this all the time, to save load time for common resources, or just for convenience. But when you’re writing privacy apps it’s better not to make these kinds of requests. Pack everything locally.

If you use only local resources within your Electron app or your browser extensions, explicitly encoding request data in a Sphinx packet does protect you from the normal leakage that gets sent in a browser HTTP request. There’s a lot of stuff that leaks when you make an HTTP request from a browser window. Luckily, all that metadata and request leakage doesn’t happen in Nym, because you’re choosing very explicitly what to encode into Sphinx packets, instead of sending a whole browser environment by default.