The fastest way to land
a transaction on Solana.

1const res = await fetch("https://send.swqos.com/v1/transactions", {
2  method: "POST",
3  headers: {
4    Authorization: `Bearer ${process.env.SWQOS_API_KEY}`,
5    "Content-Type": "application/json",
6  },
7  body: JSON.stringify({
8    transaction: Buffer.from(tx.serialize()).toString("base64"),
9  }),
10});
11 
12const { signature, charged_lamports } = await res.json();

1import { Agent } from "undici";
2 
3// Node's QUIC support is still experimental, so the fastest reliable path from
4// Node today is HTTP/1.1 with a warm keep-alive pool rather than raw QUIC. This
5// removes the TCP and TLS handshake from every send, which is most of what the
6// QUIC path buys you.
7//
8// If you want true QUIC from a JS runtime, run the Rust or Go client above as a
9// sidecar and talk to it over a local socket.
10 
11const agent = new Agent({
12  keepAliveTimeout: 60_000,
13  keepAliveMaxTimeout: 300_000,
14  connections: 4,          // a small warm pool, mirroring the QUIC guidance
15  pipelining: 1,
16});
17 
18const API_KEY = process.env.SWQOS_API_KEY!;
19 
20export async function send(tx: Uint8Array) {
21  const res = await fetch("https://send.swqos.com/v1/transactions", {
22    method: "POST",
23    headers: {
24      Authorization: `Bearer ${API_KEY}`,
25      "Content-Type": "application/json",
26    },
27    body: JSON.stringify({
28      transaction: Buffer.from(tx).toString("base64"),
29    }),
30    // @ts-expect-error undici dispatcher is not in the DOM fetch types
31    dispatcher: agent,
32  });
33 
34  if (!res.ok) {
35    const { error } = await res.json();
36    throw new Error(`${error.code}: ${error.message}`);
37  }
38  return res.json();
39}