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Browser Implementation Guide

You can build a fully working Work Card scanning system using only a web browser — no native iOS or Android app required. This page covers both the QR code and NFC card approaches, the Ergani API call, and how to handle the 15-minute submission window when connectivity drops.

No app store needed

The browser camera API and Web NFC API are available in modern browsers. A simple web app deployed on your server is enough to run a professional card scanner on a tablet at the entrance.

How it works​

Two sides:

  • Worker — shows their QR code on their phone, or taps a physical NFC card on the reader.
  • Employer tablet — reads the QR/NFC, maps it to the employee's ΑΦΜ, and posts the arrival or departure event to the Ergani API within 15 minutes.
Worker's phone      Employer's tablet            Your server         Ergani API
──────────────      ─────────────────────        ───────────         ──────────
Shows QR/NFC    →   Reads card or QR code    →   POST /workcard  →   WRKCardSE
                    Looks up employee ΑΦΜ         Greece timezone      Returns OK
                    Shows ✅ on screen            Handles JWT auth

QR Code approach​

Works on any device — iPhone, Android, desktop.

Worker side — show the QR​

Generate a QR code from the employee's ΑΦΜ and display it in their browser.

npm install qrcode
import QRCode from 'qrcode'

async function showWorkerQR(afm) {
  const canvas = document.getElementById('qr-canvas')
  await QRCode.toCanvas(canvas, afm, { width: 300 })
}

The worker opens this page on their phone and holds it up at the entrance.

Employer side — scan with the camera​

npm install html5-qrcode
import { Html5QrcodeScanner } from 'html5-qrcode'

const scanner = new Html5QrcodeScanner('reader', { fps: 10, qrbox: 250 })

scanner.render((afm) => {
  // afm is the employee's ΑΦΜ read from the QR
  handleScan(afm)
})

NFC Card approach​

Workers get a cheap blank NFC card (€0.20–0.50 each). They tap it on the employer's Android tablet — no phone needed.

Android + Chrome only

The Web NFC API (NDEFReader) works only on Chrome on Android. It is not supported on iOS — use QR as a fallback for iPhone users.

async function startNFCScanner() {
  if (!('NDEFReader' in window)) {
    showError('NFC not supported — please use QR code instead')
    return
  }

  const reader = new NDEFReader()
  await reader.scan() // prompts for NFC permission

  reader.addEventListener('reading', ({ serialNumber }) => {
    // serialNumber is the unique ID burned into the card
    // e.g. "04:A3:2F:11:BC:44:80"
    handleScan(serialNumber)
  })
}

You store a mapping of cardId → employee ΑΦΜ in your database. When a card is tapped, look up the employee and proceed.

QR vs NFC​

QR CodeNFC Card
Works on iPhone✅❌
SpeedSlower (aim camera)Faster (just tap)
Card costFree (worker uses phone)€0.20–0.50 per card
Employer deviceAny phone or tabletAndroid only
Feels professionalOK✅ Yes

Recommendation: support both. Workers without a smartphone use the NFC card. The Ergani API call is identical either way.

Calling the Ergani API​

Once you have the employee's ΑΦΜ, post the event from your backend. Never call the Ergani API directly from the browser — keep your JWT token server-side.

// Browser → your server
async function handleScan(employeeId) {
  const employee = await getEmployeeByCardId(employeeId) // your DB lookup
  if (!employee) { showError('Unknown card'); return }

  const eventType = getNextEventType(employee) // 'arrival' or 'departure'

  await fetch('/api/workcard', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({
      afm: employee.afm,
      branchId: currentBranch.id,
      type: eventType,
      timestamp: new Date().toISOString()
    })
  })

  showSuccess(`${employee.name} — ${eventType}`)
}
// Your server → Ergani API
app.post('/api/workcard', async (req, res) => {
  const { afm, branchId, type, timestamp } = req.body

  const payload = {
    f_afm_ergodoti: employer.afm,
    f_aa_pararthmatos: branchId,
    f_afm_ergazomenos: afm,
    f_date: toGreekLocalTime(timestamp), // ⚠️ see note below
    f_type: type === 'arrival' ? '0' : '1'
  }

  const response = await fetch(
    'https://eservices.yeka.gr/WebservicesAPI/Api/Documents/WRKCardSE',
    {
      method: 'POST',
      headers: {
        'Authorization': `Bearer ${erganiToken}`,
        'Content-Type': 'application/json'
      },
      body: JSON.stringify(payload)
    }
  )

  res.json(await response.json())
})
Greece timezone — not UTC

f_date must be in Greece local time (UTC+2 in winter, UTC+3 in summer with DST). Sending UTC causes submissions to appear late and get rejected. Convert before sending:

function toGreekLocalTime(isoString) {
  return new Date(isoString).toLocaleString('sv-SE', {
    timeZone: 'Europe/Athens'
  }).replace(' ', 'T')
}

Offline queue — handling the 15-minute window​

If the internet drops mid-shift, store scans locally and retry when connectivity returns.

async function submitWithFallback(payload) {
  try {
    await callErganiAPI(payload)
  } catch {
    const queue = JSON.parse(localStorage.getItem('wc_queue') || '[]')
    queue.push({ payload, queuedAt: Date.now() })
    localStorage.setItem('wc_queue', JSON.stringify(queue))
    showWarning('Saved offline — will retry when connected')
  }
}

async function flushQueue() {
  const queue = JSON.parse(localStorage.getItem('wc_queue') || '[]')
  if (!queue.length) return

  const now = Date.now()
  for (const item of queue) {
    const ageMinutes = (now - item.queuedAt) / 60000
    if (ageMinutes > 15) {
      // Mark as late — Ergani will require a justification reason
      item.payload.late = true
      item.payload.lateReason = 'EMPLOYER_SYSTEM_FAILURE'
    }
    await callErganiAPI(item.payload)
  }

  localStorage.removeItem('wc_queue')
}

window.addEventListener('online', flushQueue)
Late submission justification

If more than 15 minutes have passed, the submission is considered εκπρόθεσμη. Accepted justification codes are EMPLOYER_SYSTEM_FAILURE, POWER_TELECOM_OUTAGE, and ERGANI_CONNECTIVITY. You must also notify the Labour Inspectorate (Επιθεώρηση Εργασίας) immediately when the outage occurs and again when it ends. See Work Card overview.

Where to go next​