Receive results with a webhook

npm install express
node server.mjs

import crypto from "node:crypto";
import express from "express";

const PARSER_ID = process.env.SIMPLYPARSE_PARSER_ID;
const SECRET = process.env.SIMPLYPARSE_WEBHOOK_SECRET;

// --- Verification -----------------------------------------------------------

function safeEqual(a, b) {
  const x = Buffer.from(a ?? "");
  const y = Buffer.from(b ?? "");
  return x.length === y.length && crypto.timingSafeEqual(x, y);
}

// The signature covers the compact JSON form of the body (no spaces after
// "," and ":"). Strip whitespace outside strings to rebuild it exactly.
function compactJson(raw) {
  let out = "";
  let inString = false;
  let escaped = false;
  for (const ch of raw) {
    if (inString) {
      out += ch;
      if (escaped) escaped = false;
      else if (ch === "\\") escaped = true;
      else if (ch === '"') inString = false;
    } else if (ch === '"') {
      inString = true;
      out += ch;
    } else if (ch !== " " && ch !== "\n" && ch !== "\r" && ch !== "\t") {
      out += ch;
    }
  }
  return out;
}

function verifySignature(raw, signature) {
  const expected = crypto.createHmac("sha256", PARSER_ID).update(compactJson(raw), "utf8").digest("hex");
  return safeEqual(expected, signature);
}

// --- Storage (replace with your database) ------------------------------------

const entries = new Map(); // entry_id -> record

async function saveEntry(data) {
  // Upsert: a redelivery of the same entry_id overwrites, never duplicates.
  entries.set(data.entry_id, {
    documentId: data.document_id,
    isValid: data.is_valid,
    parsedData: data.parsed_data,
    validationErrors: data.validation_errors,
    receivedAt: new Date().toISOString(),
  });
}

async function processEntry(data) {
  // Slow work goes here: push to your ERP, notify a reviewer, etc.
  console.log(`entry ${data.entry_id} valid=${data.is_valid}`);
}

// --- HTTP ---------------------------------------------------------------------

const app = express();

app.post("/hooks/simplyparse", express.raw({ type: "*/*", limit: "5mb" }), async (req, res) => {
  if (!safeEqual(req.get("X-Webhook-Secret"), SECRET)) return res.sendStatus(401);

  const raw = req.body.toString("utf8");
  if (!verifySignature(raw, req.get("X-SimplyParse-Signature"))) return res.sendStatus(401);

  const { data } = JSON.parse(raw);
  await saveEntry(data); // persist before acknowledging
  res.sendStatus(204);

  processEntry(data).catch((err) => console.error("processing failed", data.entry_id, err));
});

app.listen(process.env.PORT ?? 8080, () => console.log("listening"));