TypeScript SDK

One npm package for the whole API: swaps, cross-chain, tokens, prices and your key. Typed end to end, and it never touches a private key.

Install

bash

npm i lcx-liberty-sdk

ESM and CommonJS both ship, with type declarations. Node 18 or newer, or any bundler.

The client

One client, six namespaces. Each is a thin wrapper over the endpoints documented in the API reference, so anything true there is true here.

import { LibertyDex } from "lcx-liberty-sdk";

const lcx = new LibertyDex({ apiKey: process.env.LCX_API_KEY });

Namespace	What it covers
`lcx.swap`	Price, build and submit a same-chain swap.
`lcx.crossChain`	Quote across chains, and follow a transfer.
`lcx.tokens`	The token registry, and what we vouch for.
`lcx.prices`	USD prices: one token, a batch, or a past day.
`lcx.chains`	Supported chains and index freshness.
`lcx.account`	Your key: plan, quota and usage.

Without an apiKey the client talks to https://dex-api.lcx.com, the anonymous product host, which is rate limited per IP. With one it talks to https://swap-api.lcx.com. That is the same split the rest of these docs describe, and the only thing the key changes.

A swap, end to end

execute is quote and build in one call. It hands back the quote it priced and the transaction that matches it, so nothing can sign a route it was not shown.

const { quote, transaction } = await lcx.swap.execute({
  chainId: 1,
  tokenIn:  "0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2", // WETH
  tokenOut: "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48", // USDC
  amount: "1",
  decimals: 18,
  taker: userAddress,
  slippageBps: 50,
});

console.log(quote.output.amount, "USDC, floor", quote.output.minimumAmount);

// { to, data, value } — hand it to whatever holds the keys.
await wallet.sendTransaction(transaction);

The SDK never sees a private key and never signs. It returns calldata; signing stays with the wallet, which is the same boundary the product itself keeps.

Approvals

Selling an ERC-20 needs an allowance for the router first. Ask before you spend gas on one: required is false when the allowance already covers the trade.

const { required, spender } = await lcx.swap.allowance({
  chainId: 1,
  token: WETH,
  taker: userAddress,
  amount: quote.input.amount, // raw units, not decimal
});

Native ETH needs no approval. See Approvals in Core concepts for the permit path and what a router upgrade means for an existing allowance.

Errors

Every failure arrives as a LibertyError carrying the API's own machine code, so a caller branches on the code rather than matching on a message that is free to change.

import { LibertyError } from "lcx-liberty-sdk";

try {
  await lcx.swap.execute(params);
} catch (e) {
  if (e instanceof LibertyError) {
    // e.code   — "no_route", "rate_limited", "price_moved", ...
    // e.status — the HTTP status
    // e.details — whatever the endpoint attached
  }
}

The codes are the ones listed under Errors in Core concepts; the SDK adds none of its own.

Swap widget