Node's node:* standard library, in 100% pure Vanilla JavaScript.

import https from "node:https";
import fs from "node:fs";
import crypto from "node:crypto";

// Map custom local domain in virtual /etc/hosts
fs.writeFileSync("/etc/hosts", "127.0.0.1:8443 api.vbs.local\n");

const server = https.createServer((req, res) => {
  const hmac = crypto.createHmac("sha256", "vbs-key")
    .update(req.url).digest("hex").slice(0, 16);
  res.writeHead(200, {
    "Content-Type": "application/json",
    "X-VBS-Signature": hmac
  });
  res.end(JSON.stringify({
    server: "vbs/0.1.0",
    method: req.method,
    url: req.url,
    tls: req.socket.encrypted,
    cert: req.socket.getPeerCertificate().subject.CN
  }, null, 2));
});

server.listen(8443);
https.get("https://api.vbs.local/v1/inspect?mode=client-only", ...);

import fs from "node:fs";
import crypto from "node:crypto";

const file = "/home/vbs/counter.json";
const prev = fs.existsSync(file)
  ? JSON.parse(fs.readFileSync(file, "utf8"))
  : { runs: 0 };

const next = {
  runs: prev.runs + 1,
  updatedAt: new Date().toISOString(),
  sha256: crypto.createHash("sha256")
    .update(String(prev.runs + 1)).digest("hex").slice(0, 16)
};

fs.writeFileSync(file, JSON.stringify(next, null, 2));
console.log(fs.readdirSync("/home/vbs"));
console.log(fs.readFileSync(file, "utf8"));

import https from "node:https";
import { Buffer } from "node:buffer";

https.get("https://registry.npmjs.org/cf/latest", (res) => {
  const chunks = [];
  res.on("data", (chunk) => chunks.push(chunk));
  res.on("end", () => {
    const pkg = JSON.parse(Buffer.concat(chunks).toString("utf8"));
    console.log({
      status: res.statusCode,
      name: pkg.name,
      version: pkg.version,
      bytesReceived: Buffer.concat(chunks).length
    });
  });
});