Blog
Development, infrastructure, SEO, AI and IT for business — short and to the point.
1495 articles
- Mobile development3 min
App Store and Google Play Fees: How Much the Stores Take
Both stores take a standard 30% commission on digital purchases, with a reduced 15% rate for small businesses and subscriptions. Apple charges a yearly developer fee, Google Play a one-time fee; payments for physical goods and services are not subject to store commission.
Basics - Marketing & analytics4 min
Cohort Analysis in Marketing: Measuring Retention and LTV
Cohort analysis groups customers by the month of their first purchase and their acquisition channel, then tracks how many return and how much revenue they bring over time. Comparing channels by cohort LTV at the same horizon against acquisition cost shows where your budget pays off best.
Advanced - Design & UX4 min
Button Design in UI: Sizes, States and Labels
A good button shows its importance through hierarchy, reacts visibly in every state (hover, focus, pressed, disabled, loading), is big enough to hit and is labeled with a verb that names the result.
Practice - Telegram & messengers4 min
How to Build a Telegram Mini App with React
A React Mini App is a regular HTTPS web app that loads telegram-web-app.js, takes colors from themeParams, drives the native MainButton and BackButton through window.Telegram.WebApp and opens from a bot.
Practice - E-commerce & CRM4 min
B2B E-commerce: How It Differs From B2C and Features It Needs
A B2B store sells to companies rather than individuals, so it needs personal pricing, minimum order quantities, quote requests, deferred payment, invoices and data exchange with the ERP.
Basics - Security4 min
Content Security Policy (CSP): A Practical Setup Guide
CSP is a response header that lists which scripts and other resources the browser may run on your page; the most robust setup is a nonce-based policy with strict-dynamic, reached gradually through report-only mode so nothing breaks along the way.
Advanced - Databases & data4 min
Common Database Design Mistakes and How to Avoid Them
Most data problems start in the schema: keep one value per cell, enforce constraints in the database, use numeric for money, consistent names, timestamps and timestamptz for time.
Practice - Hosting & cloud4 min
AWS vs Google Cloud vs Azure: How the Big Three Compare
All three clouds cover typical business workloads; AWS wins on catalog breadth, Google Cloud on data, Kubernetes and AI, Azure on Microsoft integration. Choose by your team's skills, the managed services you need and the nearest region.
Basics - IT careers3 min
Data Analyst Roadmap: How to Become an Analyst
To become a data analyst, go Excel → SQL → statistics → visualization → Python, and build a portfolio of 3-4 public-data cases where you answer specific business questions.
Practice - Tools & no-code4 min
Date Functions in Excel: DATEDIF, NETWORKDAYS, EOMONTH
In Excel a date is a number, so deadlines are simple addition, working days come from NETWORKDAYS and WORKDAY with a holiday list, age and tenure from DATEDIF, and month ends from EOMONTH.
Practice - IT by industry4 min
B2B Ordering Portal for Dealers: How Manufacturers Sell Online
A B2B portal is a dealer account where partners see their own prices, stock and balance and place orders themselves, while all data comes from the manufacturer's ERP and goes back to it without manual entry.
Practice - Networks & office IT4 min
How to Keep the Office Online: Dual WAN and LTE Backup
Connect a second ISP over a different medium (for example fibre plus LTE) to a Dual WAN router, configure automatic failover based on reachability checks and test it regularly.
Practice - IT for business3 min
What the Client Must Provide for an IT Project to Succeed
The client owns fast decisions, content, system access, test data and regular feedback — each day of delay on the client side usually moves the whole project by at least as much.
Practice - Web development4 min
How to Build a REST API with Node.js and Express
Create an Express project, split code into routes, controllers and a data layer, validate input with a schema, handle errors in a single middleware and test the endpoints with an HTTP client.
Practice - SEO3 min
Common SEO Mistakes That Kill Your Rankings
The most damaging mistakes are the ones that stop search engines from indexing your site: blocked pages, broken redirects, duplicates. Next come weak content for the wrong intent and toxic links.
Practice - DevOps3 min
What Is a Container Registry: Docker Hub, GHCR and Private Registries
A container registry stores Docker images so servers and CI can pull ready-made builds of your app. Pick a registry close to your CI or cloud, tag images by commit or version and set up automatic cleanup of old ones.
Basics - AI & automation4 min
AI Contract Review: How Lawyers Can Use LLMs Safely
An LLM speeds up first-pass contract review by extracting and structuring clauses, flagging risks against your checklist and comparing text to a template, but a lawyer checks every output against the source, and client documents go only to services with suitable confidentiality terms.
Practice - Programming3 min
Code Smells and How to Refactor Them
A code smell is a sign that structure is getting in the way of change; you fix it with small refactoring steps, each one protected by tests.
Practice - Mobile development4 min
A/B Testing App Store Pages: Product Page Optimization and Experiments
Both stores have built-in A/B tests for the store page — Product Page Optimization on iOS and Store Listing Experiments on Google Play; test one big idea at a time (icon, first screenshots, short description) and wait for a confident result before applying it.
Practice - Marketing & analytics3 min
How to Research Competitor Ads: Meta Ad Library, Google Transparency
Collect competitors' active ads in Meta Ad Library and Google Ads Transparency Center, add keyword data, put offers and promises in one table and take the position nobody has claimed.
Practice - Design & UX4 min
Card Sorting and Tree Testing: How to Validate Site Navigation
Card sorting shows how users group your content on their own, while tree testing checks whether they can find things in the resulting structure; sort first, then test the tree, then fix and retest.
Practice - Telegram & messengers4 min
How to Buy Ads in Telegram Channels Without Wasting Budget
Buy Telegram channel ads in small tests on verified niche channels, give every placement its own invite link, and judge results by cost per subscriber and cost per lead, not by reach.
Practice - E-commerce & CRM4 min
How to Set Up Bitrix24 CRM: A Practical Guide
Pick a CRM mode first (with or without leads), map your deal pipelines, add only the fields you need, automate routine work with automation rules and triggers, assign rights by role, and connect forms and Open Channels so requests land in the CRM automatically.
Practice - Security4 min
Credential Stuffing and Account Takeover: Detection and Defense
Credential stuffing replays username-password pairs leaked from other sites; stop it with layered defenses — block breached passwords via k-anonymity checks, score each login by device and behavior, ask for a second factor only when risk is high, filter bots and alert on login anomalies.
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