Installation

Install the package

npm install vellar-sdk @stellar/stellar-sdk
# or: pnpm add vellar-sdk @stellar/stellar-sdk
# or: yarn add vellar-sdk @stellar/stellar-sdk

@stellar/stellar-sdk is a peer dependency — you install it alongside so your app and the SDK share one copy.

You'll also want the passkey smart-wallet engine and Soroban token client the SDK composes:

npm install passkey-kit

What you supply

The SDK stays free of a hard dependency on a specific wallet-engine version and of any secret material. You provide three host pieces:

Piece	What it is	Why the SDK doesn't own it
kit	A PasskeyKit instance	Keeps browser-only WebAuthn code out of SSR and lets you pin the version
sac	A SACClient (Soroban token client)	Used to build token transfers
backend	Your server endpoints	The relayer/sponsor keys are secrets — they must live server-side, never in the client

The backend object implements three methods:

interface Backend {
  submitWalletCreation(input): Promise<{ sessionId: string }>;
  lookupContractId(input): Promise<{ contractId: string; sessionId: string } | undefined>;
  submitTransaction(input: { signedXdr: string; network }): Promise<{ hash: string }>;
}

These forward to your server, which holds the OpenZeppelin Relayer / sponsor credentials and submits to the network. See How It Works for why submission is server-side.

Requirements

• A secure context — WebAuthn (passkeys) only works over HTTPS or localhost. It will not work in embedded/preview browsers.
• A modern browser with platform authenticator support (all current Chrome / Safari / Edge / Firefox).
• Node 18+ if you run any of the SDK in a server environment.

Next: the Quickstart.