Validate EU VAT numbers in bulk from a CSV: the loop, the pacing, the evidence

import { readFile, writeFile } from "node:fs/promises";

const API = "https://veriport.io/api/v1";
const KEY = process.env.VERIPORT_KEY; // optional: 20 calls a day without one, 100 a month with a free key
const REQUESTER = process.env.MY_VAT_NUMBER; // your own VAT number: consultation numbers on the paid tiers
const headers = { Accept: "application/json", ...(KEY ? { Authorization: `Bearer ${KEY}` } : {}) };

// 1. Read, normalise, de-duplicate: one column, one VAT number per line, prefix included.
const raw = (await readFile("numbers.csv", "utf8")).split(/\r?\n/).map((l) => l.split(",")[0].trim()).filter(Boolean);
const numbers = [...new Set(raw.map((n) => n.toUpperCase().replace(/[\s.\-]/g, "")))];

const rows = [["number", "valid", "name", "requestDate", "source", "stale", "consultationNumber", "status"]];
const retry = [];
for (const n of numbers) {
  const url = new URL(`${API}/vat/validate`);
  url.searchParams.set("number", n);
  if (REQUESTER) url.searchParams.set("requester", REQUESTER);
  const res = await fetch(url, { headers });
  const a = await res.json();
  if (res.ok) {
    // 2. One line per number, the provenance kept: a cached answer is evidence of its own date, not today's.
    rows.push([a.full, a.valid, a.name ?? "", a.requestDate ?? "", a.source.kind, a.source.stale, a.consultationNumber ?? "", a.upstream.status]);
  } else if (a.code === "vies_unavailable" || a.code === "vies_blocked") {
    retry.push(n); // 3. the member state or VIES is down and no cached answer exists: queue, never write "invalid"
    await new Promise((r) => setTimeout(r, (a.retryAfter ?? 30) * 1000));
  } else if (a.code === "rate_limited") {
    await new Promise((r) => setTimeout(r, Number(res.headers.get("Retry-After") ?? 1) * 1000));
    numbers.push(n); // back of the queue
  } else {
    rows.push([n, "", "", "", "", "", "", a.code]); // invalid_parameter, quota_exceeded… the code says why
  }
  // 4. Pace: the free key allows 2 requests a second; VIES itself asks for one in flight per member state.
  await new Promise((r) => setTimeout(r, 550));
}
await writeFile("results.csv", rows.map((r) => r.map((c) => `"${String(c).replace(/"/g, '""')}"`).join(",")).join("\n") + "\n");
await writeFile("retry.csv", retry.join("\n") + "\n");
console.log(`${rows.length - 1} answered, ${retry.length} to retry (see /vies-status for the member states that are down)`);

import csv, os, time, requests

API = "https://veriport.io/api/v1"
HEADERS = {"Accept": "application/json"}
if os.environ.get("VERIPORT_KEY"):
    HEADERS["Authorization"] = f"Bearer {os.environ['VERIPORT_KEY']}"
REQUESTER = os.environ.get("MY_VAT_NUMBER")  # consultation numbers on the paid tiers

with open("numbers.csv", newline="", encoding="utf-8") as f:
    seen, numbers = set(), []
    for row in csv.reader(f):
        n = row[0].strip().upper().replace(" ", "").replace(".", "").replace("-", "") if row else ""
        if n and n not in seen:
            seen.add(n); numbers.append(n)

out = csv.writer(open("results.csv", "w", newline="", encoding="utf-8"))
out.writerow(["number", "valid", "name", "requestDate", "source", "stale", "consultationNumber", "status"])
retry = []
for n in numbers:
    params = {"number": n, **({"requester": REQUESTER} if REQUESTER else {})}
    r = requests.get(f"{API}/vat/validate", params=params, headers=HEADERS, timeout=30)
    a = r.json()
    if r.ok:
        out.writerow([a["full"], a["valid"], a.get("name") or "", a.get("requestDate") or "", a["source"]["kind"], a["source"]["stale"], a.get("consultationNumber") or "", a["upstream"]["status"]])
    elif a.get("code") in ("vies_unavailable", "vies_blocked"):
        retry.append(n); time.sleep(a.get("retryAfter") or 30)
    elif a.get("code") == "rate_limited":
        time.sleep(int(r.headers.get("Retry-After", "1"))); numbers.append(n)
    else:
        out.writerow([n, "", "", "", "", "", "", a.get("code")])
    time.sleep(0.55)  # 2 requests a second on the free key

open("retry.csv", "w").write("\n".join(retry) + "\n")
print(f"{len(numbers) - len(retry)} answered, {len(retry)} to retry")

curl -X POST "https://veriport.io/api/v1/vat/validate/bulk" \
  -H "Authorization: Bearer vp_live_YOUR_KEY" -H "Content-Type: application/json" \
  -d '{"requester":"FR40303265045","items":[{"number":"DE136695976"},{"number":"FR40303265045"},{"country":"IT","number":"00743110157"}]}'