This project developed a lightweight CLI tool to monitor Eslite Online's product stock status. Existing Eslite Online product pages only show stock individually, preventing bulk checks or real-time monitoring for hot items. The core technical challenge was to bypass frontend protections and correctly call the backend API. The tool directly interacts with Eslite's product API, replacing manual webpage refreshing.A significant issue encountered was a 403 Forbidden error from Cloudflare due to TLS fingerprint detection. Standard Python libraries produce TLS fingerprints that differ from real browsers, leading Cloudflare to block the requests. The solution involved using curl-cffi with the impersonate="chrome120" parameter to mimic a Chrome browser's TLS and HTTP/2 fingerprints. Eslite's API requires a dynamic timestamp parameter in YYYYMMDDHHMMSS format for request validation or cache invalidation. The tool generates this timestamp in real-time for each API call.To simplify user input, the tool uses regular expressions to extract a 20-digit GUID from either a raw GUID or a full product URL. A --watch N parameter was added for continuous monitoring, querying the stock every N seconds and refreshing the terminal display. Stock and purchase statuses are color-coded for easy visual scanning. The tool supports querying multiple products simultaneously, with individual product query failures being isolated without interrupting the entire batch.To ensure compatibility on Windows terminals that may not default to UTF-8 encoding, the script actively reconfigures standard output and error streams to use UTF-8. The project adheres to PEP 723, allowing users to execute the script using uv run without needing to pre-install dependencies. The most critical and least obvious technical decision was overcoming the TLS fingerprinting issue, which required a specialized library rather than just faking HTTP headers.