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Laxman Patel
Laxman Patel

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How I Built a Python CLI for Blazing-Fast Crypto Exchange Price Notifications

We’ve all been there — staring at a price chart, switching tabs, doing other work… and boom — the market moves.
You come back, and it’s either a missed profit or an unnecessary loss.

That was me, multiple times, while trading on Delta Exchange. Delta Exchange offers a great trading experience but lacks real-time custom alerts for specific price points.

I knew I couldn’t sit and watch the chart all day.

Output

I wanted a fast, resource-efficient, and reliable way to track prices and trigger alerts without constantly refreshing charts or relying on third-party apps.

Tech Stack Used

  • Python – Core programming language.
  • WebSocket – For real-time price streaming.
  • JSON – To store and manage alert configurations.
  • Plyer – For cross-platform desktop notifications.

Backend Logic

Here’s how the tool works under the hood:

  • Connect to Delta Exchange WebSocket feed to get real-time price data.
  • Compare latest price with stored alert conditions from a local JSON file.
  • Trigger an alert when the price crosses the target threshold.
  • Mark the alert as “triggered” so it’s not repeatedly fired.
  • Send notifications via:
    • Desktop notification using Plyer.
    • Email notification for remote alerts.

Why WebSocket Instead of REST API?

Initially, I considered using the REST API for fetching prices, but there were a few drawbacks:

  • REST is pull-based – I’d have to make repeated requests to get the latest price.
  • This leads to API rate limits and unnecessary network usage.
  • Even with short intervals, REST polling introduces latency in updates.

On the other hand, WebSocket:

  • Pushes data in real-time as soon as the price changes.
  • Reduces server load and network calls.
  • Ensures alerts trigger instantly without delays.

For a price alert system, real-time updates are critical — so WebSocket was the obvious choice.

Sample Output

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Future Developments

While the CLI works perfectly for my needs, I plan to:

  • Containerize the application with Docker for easy deployment.
  • Create a web-based UI for broader accessibility and a better user experience.

If you trade on Delta Exchange (or any platform without great alerting), I highly recommend building something like this. It’s not just about automation — it’s about peace of mind.

Checkout my project repo on GitHub

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