Blog
Development, infrastructure, SEO, AI and IT for business — short and to the point.
1495 articles
- Databases & data4 min
Database Indexes Explained: How They Speed Up Queries
An index is a separate sorted structure, usually a B-tree, that lets the database jump straight to matching rows instead of reading the whole table; it speeds up reads but slows down every insert, update and delete, so add indexes for real queries, not just in case.
Basics - Hosting & cloud4 min
Cloud Credits for Startups: AWS, Google Cloud and Azure Programs
The big clouds give startups credits, a prepaid balance for their services with an expiry date; they are easier to get through an accelerator or investor, and the key is to design your architecture as if you were paying from day one.
Basics - IT careers4 min
How to Write a Cover Letter for a Developer Job
A developer cover letter is 5-8 sentences written for one specific vacancy: why this company, which of your experience or projects solves their problems, and what you propose next; a generic template is worse than nothing.
Practice - Tools & no-code4 min
How to Fix #N/A, #REF!, #VALUE! and Other Formula Errors
Each spreadsheet error points to a specific problem: #N/A means a value wasn't found, #REF! means a reference to deleted cells, #VALUE! means the wrong data type; trace the source with formula auditing tools first, then decide whether to catch the error.
Practice - IT by industry4 min
How to Set Up Barcode Labeling and Scanning in a Store
Clean up the product catalog first, use manufacturer EANs where they exist and internal codes for the rest, then choose scanners and a label printer and scan goods at every step from receiving to checkout.
Practice - Networks & office IT4 min
IT Onboarding and Offboarding Checklist for Employees
On day one a new hire gets ready accounts, a device, role-based access and licenses from a prepared list; on departure you walk the same list backwards — revoke access that day, hand over data and collect the equipment.
Practice - IT for business4 min
Who Owns Your Data in a SaaS Service: Contract Checklist
Your data should stay yours in writing: the contract must state that you own it, let you export it in an open format at any time, define what happens to it after cancellation and name where and by whom it is stored.
Advanced - Web development3 min
Bun vs Deno vs Node.js: JavaScript Runtimes Compared
For most production projects Node.js is still the safest choice; Bun stands out for speed and built-in tooling, Deno for its security model and out-of-the-box TypeScript.
Basics - SEO4 min
How to Analyze Competitors' Keywords and Find Content Gaps
Find the sites that actually rank for your target queries, export their keywords, compare them with yours and turn the missing topics into a plan sorted by business value.
Practice - DevOps4 min
Cron Jobs in Linux: How to Schedule Tasks Correctly
Add jobs with crontab -e, use absolute paths, redirect output to a log file and wrap long jobs in flock so they never run in parallel.
Practice - AI & automation4 min
How to Add AI Features to a Mobile App: Cloud vs On-Device
Cloud models are smarter and easier to launch but need a network and a backend proxy for keys; on-device models are fast, offline and private but limited in capability and supported devices.
Practice - Programming4 min
Singleton, Factory, Strategy, Observer: Patterns in Practice
Strategy swaps algorithms, Factory picks the right implementation, Observer broadcasts events to subscribers and Singleton guarantees one instance. Each helps only for a specific problem, and Singleton is often better replaced with dependency injection.
Practice - Mobile development4 min
Common App Store and Google Play Rejection Reasons and How to Fix Them
Most rejections come from crashes, missing demo access, wrong payment flows, privacy issues and thin functionality; nearly all of them are prevented by a pre-submission checklist and fixed with a precise, polite reply to the reviewer.
Practice - Marketing & analytics4 min
How to Build a Content Marketing Strategy Step by Step
A content marketing strategy answers four questions: who you write for, which funnel task each piece solves, where people will see it, and how you will know it works; everything else is execution.
Practice - Design & UX4 min
How to Check Color Contrast for WCAG Compliance
Under WCAG 2, normal text needs at least 4.5:1 contrast (AA) or 7:1 (AAA), large text 3:1 or 4.5:1, and UI components and meaningful graphics 3:1; check every real text and background pair with a contrast tool and darken or resize what fails.
Practice - Telegram & messengers4 min
How to Connect ChatGPT or Claude to a Telegram Bot
The bot's backend receives a message, loads that user's recent history, calls the LLM API with a key stored only on the server, streams the answer by editing one message, and enforces per-user limits and input checks.
Practice - E-commerce & CRM4 min
Buy Now, Pay Later and Installments in Online Stores Explained
The customer takes an installment plan from a third-party service, the service pays the store the order amount upfront minus a fee and then collects payments from the customer, taking on the risk of non-payment.
Basics - Security4 min
Cybersecurity Basics for Small Business: Where to Start
Start with six basic steps in this order: list every account, turn on 2FA everywhere, enable automatic updates, keep backups you have actually restored, revoke access when people leave and protect devices, with one named person owning each task.
Basics - Databases & data4 min
Database Migrations: How to Change Schema Safely
Change the schema only through numbered migrations in your repository, apply them automatically on deploy, and split risky changes into compatible steps so old and new code can both work with the database.
Practice - Hosting & cloud3 min
Cloud Regions and Availability Zones Explained
A region is a cloud provider's geographic location, and availability zones are isolated data centers inside it. Pick a region by proximity to users, price and legal requirements, and use several zones so your service survives the failure of one data center.
Basics - IT careers4 min
Developer Portfolio: Which Projects to Include and How
A portfolio needs 2–4 finished projects that solve a clear problem, each with a README, a working demo and a short write-up of your decisions — not a dozen copies of tutorials.
Practice - Tools & no-code4 min
How to Make Charts in Excel and Google Sheets
First decide what you need to show (a comparison, a trend, a share or two metrics at once), then prepare a clean table with headers and insert the chart: Insert tab in Excel, Insert → Chart in Google Sheets.
Basics - IT by industry4 min
Beauty Salon Software: How to Choose a Booking and CRM System
Good salon software combines online booking, staff schedules, client cards, materials inventory and payroll in one database, and you should choose it by your processes, not by the length of the feature list.
Practice - Networks & office IT4 min
Ethernet Cable Categories: Cat5e vs Cat6 vs Cat6a
Cat5e reliably carries 1 Gbps over 100 m, Cat6 handles 10 Gbps only on short runs, and Cat6a delivers 10 Gbps over the full 100 m; for a new office, solid-copper Cat6a or at least Cat6 is the sensible choice.
Basics
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