TypeScript SDK

Install

npm i lcx-liberty-sdk

The current release is 1.4.0, published on 24 October 2026; Versions, below, says what each release changed. It is an ES module with type declarations and no dependencies, for Node 18 or newer, Deno, Bun, Workers or any bundler. From CommonJS, load it with await import("lcx-liberty-sdk"): a plain require throws a message saying so.

The client

One client, seven 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 });

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
  amountIn: "1000000000000000000", // base units; or amount: "1"
  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);

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
});

The chain's native coin 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.

Versions

Upgrading changes nothing in a call. Every method takes a plain chainId, and the router a swap goes through (spender and to) always comes from the API, never from the package, so code that never hardcoded an address keeps working.