PKD is an employee platform for a vegetable grower. Staff track their time by scanning an NFC tag or QR code at the greenhouse row, even offline. The scans feed time records, workflow diagrams and timesheets. The platform also includes team chat and calls, training videos in each worker's language, a camera-based pack counter with AI, and company phones in kiosk mode. Server, web app, Android and iOS — built by one developer.
A horticultural business employs permanent and seasonal staff who speak different languages. Work at the greenhouse rows was recorded on clipboards, the payroll software has no integration interface, and Wi-Fi coverage is patchy. PKD replaces paper notes with scans of the NFC tags at each row and turns those scans into what the office and management need: working hours, timesheets and a clear view of the workday.
Fig. 1 — the working day as a diagramEmployees → Working time → Workflow
Each band represents a person, each node an activity, and the band width shows recorded minutes. The diagram shows who worked where, what they did, for how long, and what still needs review.
Fig. 2 — down to each rowOne department, “Rows” view
For each row, the diagram shows minutes worked, time windows and how often work took place there that day. Rows are sorted by their first scan, so the view follows the day's sequence from top to bottom.
Fig. 3 — the employees' appNow · Today · Learn
Three questions: Am I clocked in? What am I working on? What have I done today? Chat, photos and training videos are available from the bottom bar.
Fig. 4 — in each worker's languageGerman, Polish, Ukrainian, Romanian
The account determines the language of the interface, training videos and messages; it does not depend on the device.
What the platform does
Track, analyse, communicate.
Time tracking at each row
Staff clock in, clock out and record activities by scanning the NFC tag at the row or a QR code. The server sets the recorded time. Offline scans wait on the device for upload.
Workflow, history, today
A diagram of the day by department or row, days shown side by side, transitions from yesterday to today, and a live view of who is present and what work is under way.
Timesheet and payroll
A monthly timesheet for each person, covering every calendar day. Every change requires a comment. Approval, PDF and Excel export, and reconciliation with payroll software.
Team chat and calls
One-to-one and group chats, voice messages, files and internet calls. Key contacts appear at the top: management, team lead and support.
Training in each worker's language
Short videos covering first steps and essential information, available in every language supported by the app.
Camera-based pack counter
A camera above the conveyor belt counts packs, uses AI to classify them by size and flags defects. Results appear live, in historical views and in photo reports.
Locations and chips
A site plan shows departments and rows. A card with an NFC tag hangs at each row; administrators can program the tags through the management interface.
Company phones and operations
Company phones in kiosk mode, staged updates and one account per phone. A server provides daily backups, with a copy held by a second provider.
Fig. 5 — the pack counterScreen recording, no sound
The camera records packs on the conveyor belt. A nearby computer counts and classifies them, and the server stores the results. Captured images remain in the archive as a record and can be reclassified later.
Fig. 6 — history and site planPacks counted each day · site plan with NFC tags at each row
Fig. 7 — the monthly sheetEmployees → Working time → Hours
Each calendar day has its own row. Only entries that need review are flagged: a missing clock-out, an unusual scan or a late entry. A weekend is not an error.
Technology
How the platform is built
A central server holds the authoritative record. Lightweight clients run on phones and PCs. The data model never reinterprets a scan.
The admin interface and phone app share the same web app. Native wrappers add capabilities the browser does not provide. One web deployment serves every platform.
2. The scan model
An NFC tag carries no business meaning, only an identifier: the slot. Its meaning is stored in a definition with an effective date. Every scan is an immutable event.
The phone sends the slot, event ID and its local timestamp. The server sets the authoritative time.
The hub writes the event with person, slot, definition, time and source.
Durations are calculated when records are queried. If a row is repurposed, earlier events retain their original meaning.
If the same scan arrives twice, it counts once.
3. Without a network
Queue
Every scan is saved on the device first and appears complete there immediately. Upload happens later, in scan order.
Times
The server checks the device clock, bounds implausible timestamps and flags them for review.
Cold start
The app starts and scans even after days without a network. An automated test checks this on every change.
Catalogue
Activities, locations and translations are stored on the device. Administrators can see each device's catalogue version and pending scans.
4. Evaluation
The hub handles all calculations. Workflow diagrams, history, timesheets and emailed reports use the same functions.
Workflow
A Sankey diagram connects people, activities and departments or rows. Details are shown at each node. Multiple days appear side by side, never merged into one diagram.
History
Where did work on an activity end, and did it resume in the same row? A continuation means the same activity in the same row.
Timesheet
Working days from the employment period or the company rule, public holidays from a table. Every correction needs a comment and stays visible.
Payroll software
It has no usable integration interface. A small computer on the company network reads its database and processes write requests from the hub.
5. Chat, calls, learning
Chat
One-to-one and group chats, read receipts, voice messages, files. Attachments live in an object store and are scanned for viruses.
Calls
Voice calls over WebRTC, encrypted between the devices. If the direct connection fails, a self-hosted TURN relay steps in.
Push
Calls and important messages wake the device. If push fails, the app detects calls by polling.
Learning
Short explainer videos, automatically narrated in each language.
Messages
Time-correction notices go out in the worker's language; replies are translated on the way back. An AI assistant can call to resolve questions.
6. Devices
Kiosk mode
A dedicated kiosk app as device owner: only PKD and approved apps, battery and volume monitored, updates staged.
One account per phone
Switching phones uses a QR code and signs out the old device. Spare sheets of QR codes are available.
Device keys
Every device is paired once and receives its own key. The administration can block it at any time.
7. Operations
Containers
Hub, database, proxy, object store, virus scanner, TURN relay, tunnel and backup in one Docker Compose stack.
Backup
A daily database dump on the server and an encrypted copy at a second provider.
Migration
A signed notice informs the apps when the server address changes. Devices then switch automatically.
8. Fact sheet
Role
Concept, architecture, implementation, operation and support
Users
Seasonal and permanent staff, foremen, office, management; German, Polish, Ukrainian, Romanian
