How to Integrate Express Relay Swaps

Step 1: Install the Express Relay SDK

Pyth provides a Typescript SDK to help developers integrate Express Relay into their frontends.

You can install the SDK via npm or yarn. You can invoke the SDK client as below:

import { Client } from "@pythnetwork/express-relay-js";

const client = new Client(
  { baseUrl: "https://per-mainnet.dourolabs.app" },
  undefined, // Default WebSocket options
);

Step 2: Request a Quote

You can request a quote by calling the getQuote SDK method.

The example below shows how you can construct a quote request for a USDC → WSOL swap, with 100 USDC provided as input by the user:

const userWallet = new PublicKey("<INPUT USER PUBKEY>");

const quoteRequest = {
  chainId: "solana",
  inputTokenMint: new PublicKey("EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v"), // USDC mint
  outputTokenMint: new PublicKey("So11111111111111111111111111111111111111112"), // WSOL mint
  specifiedTokenAmount: {
    side: "input",
    amount: 100_000_000,
  },
  userWallet,
};

const quote = await client.getQuote(quoteRequest);

quote contains the full details, including the amount the searcher is quoting and the transaction that the user needs to sign. It also contains an expirationTime; after this time, the transaction will no longer succeed on chain, so you should request a new quote a few seconds before the expirationTime.

Step 3: Submit User Signature to the Express Relay Server

Once you show the quote to the user, the user should sign the transaction if they wish to engage in the swap. The frontend can pass this signature along to the Express Relay server, which will handle aggregating all the required signatures for the transaction and submitting it to the RPC node.

Below is an example showing how the frontend can submit the signed quote transaction to the server using the submitQuote method. The response from the getQuote method includes a field called referenceId, which the frontend should use in its submission of the user signature.

const submitQuote = {
  chainId: "solana",
  referenceId: quote.referenceId,
  userSignature: signature,
};

const txSubmitted = await client.submitQuote(submitQuote);

submitQuote returns the fully signed transaction that the server submitted to the RPC node.

Additional Resources

You may find these additional resources helpful for integrating Express Relay as a frontend.

Contract Addresses

The Contract Addresses page lists the relevant addresses for Express Relay integration.

Error Codes

The Error Codes page lists the error codes returned by Express Relay.

API Reference

The API Reference provides detailed information on Express Relay APIs.