Learning & Course Resources
The DeelCart Blog provides practical information about online learning, courses, course resources, and useful educational opportunities.
Preventing VPS CPU Spikes: Implementing and Auditing Compound Indexes in MongoDB
Sustained high CPU with no traffic to explain it often means a collection scan. Here's how I design and audit the index that stops it.
Writing a Custom Bash Script to Monitor Server Uptime and Send Discord/Slack Webhook Alerts
One of my four sites went down for twenty minutes before I noticed. I built a bash script so that never happens silently again.
Visual Regression Testing with Playwright: Catching UI Breakages Automatically
A CSS change silently broke a layout nobody tested by eye. Here's how I set up Playwright to catch visual breakages before they ship.
Securing SSH Access on a Public Linux VPS: Disabling Passwords Safely
The moment a new VPS goes live, bots start brute-forcing SSH. Here's the exact sequence I use to go key-only without locking myself out.
Playwright and Streaming Hydration: Why One Hydration Marker Isn't Enough
My hydration marker worked fine until a page had a slow-loading section. One button was ready, another one silently wasn't. Here's the real fix.
Setting Up Automated Let's Encrypt SSL Renewals Behind Nginx Reverse Proxies
I assumed Let's Encrypt certs just renewed themselves. One expired anyway, on a server running four separate domains. Here's what I fixed.
Handling Content Layout Shifts (CLS): Debugging and Fixing Core Web Vitals with Playwright
PageSpeed Insights kept flagging a layout shift I couldn't reproduce by eye. Here's how I used Playwright to actually catch it in the act.
Handling Dynamic Element Hydration and Network Latency Flakiness in E2E Automation Testing
My E2E tests passed locally and failed randomly in CI. The cause was clicks landing before hydration and slow responses. Here's how I made them reliable.
How to Set Up Automated Daily Backups for MongoDB to an External S3 Object Storage Bucket
My databases only ever lived on the same server as my apps. One bad night would have meant losing everything. Here's how I fixed that with S3 backups.
Hardening Your Nginx Reverse Proxy: Implementing Essential Security Headers for Next.js Apps
My Nginx reverse proxy worked fine functionally but scored an F on a security headers scan. Here's what was missing and how I fixed it properly.
Handling Infinite Scroll and Lazy-Loaded Content Reliably in Playwright
My scraper only ever captured the first page of results on sites with infinite scroll. Fixed delays didn't fix it reliably. Here's what actually works.
Setting Up a Swap File on a Low-Memory Linux VPS to Prevent Node.js Out-of-Memory Crashes
One of my apps kept dying with no error, just gone. Turned out the OOM killer was ending it. Here's how a swap file fixed it for good.