Skip to content
Knowledge Base

Technical guides & open-source hub

Practical, field-tested guides spanning beginner Linux navigation to production PostgreSQL indexing, local Ollama LLMs, and open-source infrastructure.

Categorized Technical Articles

Sort:
Level:
Engineering & Architecture2 min read

Scannable Barcode & QR Code Engineering for Retail POS Systems

A deep dive into GS1 Code-128B, EAN-13 parity tables, and ISO/IEC 18004 Reed-Solomon 2D QR matrix generation in pure TypeScript.

Open-Source Tools & Setup4 min read

BCS, Teletalk & Passport Photo and Signature Size Guide in Bangladesh

Complete technical guide to resizing, cropping, and compressing BCS 300x300px photos (<100KB) and 300x80px signatures (<60KB) for Teletalk job portals and E-Passports.

E-Commerce & Retail3 min read

Bangladeshi E-Commerce Engineering: Daraz Catalog SEO & Cash-on-Delivery Math

Mastering the mathematics of Cash-on-Delivery (COD) return rates, courier reverse logistics fees, and high-converting Daraz/F-Commerce catalog optimization.

Open-Source Tools & Setup3 min read

Bijoy to Unicode Bangla Font Typing, Conversion and Official Application Guide

Comprehensive guide to SutonnyMJ ANSI legacy encoding, Avro Unicode UTF-8 standards, and drafting official Bangladeshi administrative applications.

Database & Backend Engineering4 min read

Building 24-Hour Ephemeral Content Sharing and Multi-Tier RBAC with PostgreSQL and Drizzle ORM

How to architect zero-cost ephemeral data sharing with automatic TTL expiration, PIN authorization, and multi-tier SaaS role-based access control (RBAC) in serverless PostgreSQL.

Architecture & Software Design4 min read

Architecting a Keyboard-First Raycast Omnibar and Command Palette in Next.js

How to engineer a zero-latency Command Palette 2.0 with instant arithmetic evaluation, authentic Bengali Taka-in-words, and cross-studio fuzzy navigation.

Open-Source Tools & Setup3 min read

DESCO, DPDC & Palli Bidyut Electricity Bill Slabs and Home IPS Solar Sizing Guide

Master BERC residential LT-A electricity bill step tariffs, VAT and demand charges, and size Home IPS inverters and tubular battery capacities.

Frontend Architecture & Web APIs3 min read

Designing High-Contrast Bilingual Bangla-English Interfaces for WCAG AAA

Architectural principles for engineering high-contrast bilingual interfaces supporting Bangla and English typography across light and dark modes with WCAG AAA conformance.

Open-Source Tools & Setup4 min read

Freelancer Remittance: Payoneer & Wise to Bank with 2.5% Cash Incentive in Bangladesh

An engineering and financial breakdown of receiving freelance payouts in Bangladesh: calculating Bangladesh Bank's 2.5% cash incentive, foreign exchange spreads, and mobile wallet cashout fees.

Open-Source Tools & Setup3 min read

Gold Vori Zakat Nisab, Sanchaypatra Profit and Household Budget Guide in Bangladesh

Authentic BAJUS Gold/Silver Nisab evaluation, 2.5% Zakat calculation, National Sanchaypatra tiered profit with TDS, and 50/30/20 family budgeting rules.

Open-Source Tools & Setup3 min read

House Rent Agreement, Dual-Copy Receipts and DMP Tenant Registration Guide in Bangladesh

Complete legal guide to drafting non-judicial stamp tenancy agreements, dual-copy rent receipts in Bangla words, and Dhaka Metropolitan Police (DMP) tenant verification forms.

Engineering & Architecture3 min read

How Autonomous AI Agents Keep THE SABBiR OS Self-Updating Without Paid APIs

Architectural deep-dive into client-side multi-agent swarms, deterministic vector SVG generation, GitHub Actions cron schedules, and zero-egress WebCrypto.

Autonomous Systems & AI2 min read

Multi-Agent Autonomous Swarms for Small Business & DevOps Automation

How sequential Directed Acyclic Graph (DAG) pipelines of specialized autonomous AI agents handle complex retail and DevOps workflows with zero hallucinated data leaks.

Open-Source Tools & Setup3 min read

NID, Smart Card & Document Dual-Side A4 Print and Anti-Misuse Watermark Guide

Technical guide to aligning Front and Back of National ID, Smart Cards, Driving Licenses, and Student IDs onto a single A4 sheet with anti-misuse diagonal security watermarks.

DevOps, Linux & Docker4 min read

Preventing SQL Injection and DDoS Attacks in Next.js Serverless Edge Applications

An in-depth security architecture guide to defending serverless Next.js edge applications: Token-Bucket and Sliding-Window DDoS throttling, AST SQLi payload inspectors, and Drizzle ORM parameterized prepared statements.

Open-Source Tools & Setup3 min read

SSC & HSC 4th Subject GPA Mathematics and University CGPA Calculation Guide

Master the Bangladesh Education Board GPA 5.00 formula, 4th-subject bonus point algebra, Golden A+ rules, and UGC 4.00 semester CGPA target solving.

Local AI & Architecture3 min read

True Client-Side AI Tools with WASM and Canvas: Zero Cloud Cost & 100% Privacy

How to build high-performance background removal, image segmentation, and OCR engines entirely inside the user's browser using WebAssembly, WebGPU, and HTML5 Canvas.

Basic & Beginner Guides2 min read

How to Run Local AI with Ollama: A Zero-Subscription Beginner Guide

Run powerful LLMs (Llama 3.2, Qwen 2.5, DeepSeek) 100% locally on your laptop without paying subscriptions or sending proprietary data to third-party cloud APIs.

Basic & Beginner Guides3 min read

SQL Indexing Explained Simply: From Sequential Scans to 0ms Queries

Why does your PostgreSQL query take 3 seconds instead of 3 milliseconds? An intuitive, visual explanation of B-tree database indexing, composite keys, and EXPLAIN plans.

Open-Source Tools & Setup3 min read

Automating Dokan Khata and Cash Memos to Excel with AI

How retail shop owners and SMEs in Bangladesh can parse handwritten or typed Bangla ledger notes directly into structured Excel spreadsheets with auto-totals.

Web & Mobile Development5 min read

Client-Side Media Engineering: Building Non-Destructive Canvas Image Editors and Web Audio DAWs

How to build high-performance, non-destructive creative studios in the browser without third-party cloud APIs: HTML5 Canvas LUT filters, high-DPI cropping, and Web Audio API waveform editing.

Local AI & Automation2 min read

Building Autonomous AI Micro-Agents Without Paid APIs

How to architect deterministic local-first AI micro-agents using browser WebAssembly, client-side regex ASTs, and local Ollama models with zero subscription costs.

DevOps, Linux & Docker2 min read

Docker Security Hardening in 2026: Non-Root, Distroless and Least Privilege

A comprehensive production security checklist for containerizing modern backend applications: unprivileged users, multi-stage builds, CVE scanning, and minimal base images.

Open-Source Tools & Setup3 min read

How to Remove Backgrounds and Optimize Product Photos for E-Commerce

A complete practical guide to removing image backgrounds client-side, adding studio lighting accents, and batch-compressing product photos to WebP for Daraz and Facebook Shop.

NOC, MikroTik & Hardware2 min read

MikroTik & ISP Uptime Monitoring with Telegram Outage Alerts

How to set up sub-second latency and jitter monitoring for MikroTik RouterOS gateways, with automated Telegram alerts during ISP link degradation or fiber cuts.

Basic & Beginner Guides3 min read

Linux Terminal Basics in 10 Minutes: A Beginner's Survival Guide

Master the essential Linux command-line concepts in 10 minutes: navigating directories, file operations, pipe redirects, and viewing service logs without fear.

Networking2 min read

CIDR in Five Minutes: Subnetting Without a Calculator

How to read a /24, /26 or /29 in your head: block sizes, network and broadcast addresses, and usable hosts — the arithmetic behind every subnet calculator.

DevOps2 min read

Docker Volumes vs Bind Mounts: Which One, When

Named volumes for data the container owns, bind mounts for files you edit on the host — with the permission and backup gotchas that decide it in practice.

Local AI2 min read

Local LLMs and VRAM: The Back-of-the-Envelope Math

Why a 7B model can run on an 8 GB GPU: parameters × bytes per weight, plus the KV cache that grows with context length — and how quantisation changes the numbers.

Linux2 min read

Reading systemctl status Like an On-Call Engineer

Load state, active state, main PID and the last log lines: what each part of systemctl status tells you, and the three commands to run next when a service is down.