Contact person: .NET API & POS UI Development

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Location: Chisinau, Moldova, Republic of

Budget: Recommended by industry experts

Time to start: As soon as possible

Project description:
"Technical Task for .NET Freelancer
Project: POS Customer Display System – Web Interface

Context
You have a Postman collection (Client [login to view URL]) that describes a set of endpoints for a customer display used at POS/cash registers, along with a sample UI screenshot. The goal is to develop a Windows (.exe, self-hosted) application that exposes a REST API and displays the cart and related information via a web interface accessible from a browser or directly from within the application.

Functional Requirements
Web interface (browser) for customer display:


The application must host and serve a web interface locally (e.g., http://localhost:5000), which displays the cart, total, discount, paid amount, etc., as shown in the screenshot.


The interface must be accessible from any browser (on the same machine or, optionally, the network) or directly from within the application (e.g., by opening an integrated WebView).


No native Windows interface is required. All data shown in the UI must be controlled exclusively via the APIs defined in the Postman collection.


The UI must instantly update/react to the data received through the API (e.g., /api/UpdateData should update the interface immediately).


REST API (self-hosted, on Windows) with the following endpoints:


/api/UpdateData (POST): Updates the cart data displayed in the web interface. The currentRowNumber parameter should visually highlight the corresponding row.


/api/UploadSettings (POST): Updates media display settings.


/api/UploadMediacontent (POST): Uploads a media archive for idle/cart modes.


/api/UploadLicense (POST): Uploads the .license file for activation.


/api/CheckHealth (GET): Checks the application's health and opens the web interface in the browser or inside the app (WebView/automation).


Licensing


Integrate an offline licensing mechanism:
The GetInfo endpoint must return a unique hardware identifier.
A “keygen” utility must be developed to generate .license files based on this hardware ID.
Without a valid license, the app must run in DEMO mode (the UI must display a DEMO watermark).

Media/Idle

The web interface must be able to display media (images/videos) both in idle mode and cart mode, according to the settings provided through the API.


Configurable


All display, layout, timeouts, etc., must be adjusted through the API (not directly from the UI).



Technical Requirements
.NET 8 LTS (C#)


Self-hosted REST API (Kestrel/HttpListener/other embedded solution, no IIS)
UI: Web (Blazor, ASP.NET Razor Pages, SPA or another modern web framework)
Installable application, must auto-start (Windows Service or shortcut in Startup)
Local persistence for settings/license (JSON/config files)
Keygen utility (separate, CLI or GUI) for license generation


Security:

Follow best practices for API security (input validation, endpoint protection, secure storage of license/settings, encryption as needed).


API access must be protected at least by “AccessPassword” (see Postman collection), with the possibility to extend to more advanced methods.


The executable and main components must be obfuscated (using dotnet obfuscator or equivalent) to reduce the risk of decompilation/reverse engineering.


Licensing logic or sensitive data must not be exposed in plain text.

Resources
[Postman Collection + JSON request samples] – see the attached file


[UI demo screenshot] – see the attached file


Deliverables
Fully documented C# .NET 8 source code


Installable application (setup .exe)


Keygen utility for license generation
Final executable with code obfuscation (specify method in README)" (client-provided description)