Node.js SDK

Install#

npm install @myntkaup/api

• ESM, with TypeScript types included.
• No runtime dependencies: signing uses node:crypto and requests use the global fetch.
• Server-side only. A private key never belongs in a browser.

Configure#

import { Myntkaup } from "@myntkaup/api";

// Reads MYNTKAUP_API_KEY_ID and MYNTKAUP_API_PRIVATE_KEY from the environment…
const client = new Myntkaup();

// …or give everything explicitly.
const explicit = new Myntkaup({
  keyId: process.env.MYNTKAUP_API_KEY_ID,
  privateKey: process.env.MYNTKAUP_API_PRIVATE_KEY,
  timeoutMs: 30_000,
  maxRetries: 2,
});

Methods#

quotes.create takes quoteAmount or baseAmount, exactly one. Each endpoint's reference page has a sample.

Fields and amounts#

• Request fields are camelCase and sent as the API's snake_case: quoteAmount becomes quote_amount.
• Responses are returned as the API sends them, in snake_case, so the JSON examples in these docs apply as they are: quote.base_amount, trade.filled_at.
• Amounts are decimal strings, in both directions. Never pass numbers.

Helpers#

client.buy() and client.sell() create a quote and accept it. If the trade comes back pending, they poll it for up to 30 seconds with backoff, and return the trade.

const trade = await client.buy({ asset: "BTC", quoteAmount: "100.00" });
if (trade.status !== "filled") console.warn("Not filled yet:", trade.id, trade.status);

Retries and idempotency#

• Requests are retried at most maxRetries times, with exponential backoff and jitter, honouring Retry-After.
• A GET is retried on 429, 502, 503, 504 and network errors. A POST is retried only when it has an Idempotency-Key.
• 401, 403, 409, 422 and 429 key_suspended are never retried.
• trades.create and giftcards.create send a random Idempotency-Key unless you pass idempotencyKey; quotes.create sends one only if you pass it. See Idempotency.

Errors#

Every non-2xx answer throws an ApiError with status, code, message, requestId, and retryAfter (seconds) plus the rate-limit headers when present. Network failures throw ConnectionError.

import { ApiError, NotFoundError } from "@myntkaup/api";

try {
  await client.trades.get("tr_01JB8X2Q4M7Z3V9K5T1N6R0P2W");
} catch (error) {
  if (error instanceof NotFoundError) console.log("No such trade");
  else if (error instanceof ApiError) console.error(error.code, error.requestId);
  else throw error;
}

Signing only#

To use another HTTP client, the package exports its signing function. It returns the four MK-* headers:

import { signRequest } from "@myntkaup/api";

const body = JSON.stringify({ asset: "BTC", side: "buy", quote_amount: "100.00" });
const headers = signRequest({
  keyId: process.env.MYNTKAUP_API_KEY_ID!,
  privateKey: process.env.MYNTKAUP_API_PRIVATE_KEY!,
  method: "POST",
  pathAndQuery: "/v1/quotes",
  body,
});

Testing#

Pass your own fetch to test code that uses the client without network access:

const client = new Myntkaup({
  keyId: "mk_test_0123456789abcdefghij",
  privateKey: "mk_sk_nWGxne_9WmC6hEr0kuwsxERJxWl7MmkZcDusAxyuf2A", // RFC 8032 test key, public
  fetch: async () =>
    Response.json({
      status: "ok",
      read_only: false,
      trading_enabled: true,
      giftcards_enabled: true,
      server_time: "2026-11-03T10:15:10Z",
    }),
});