Apps & Engineering Projects

Over 10+ years in software engineering, I have designed, built, and maintained production systems across cloud backends, developer utilities, automated messaging bots, browser extensions, and distributed infrastructure. Below is a curated directory of public applications and technical implementations.

Web Utilities & Microservices​

Production client-side utilities and serverless APIs with live interactive tools and reverse-engineered architecture documentation.

• Free Online PDF to SVG Converter - Vector Extraction — Convert PDF pages into high-quality, scalable vector SVG files directly in your browser. Extract clean XML markup, vector paths, and downloadable ZIP archives.
• EPUB to PDF Converter - Free, Private, In-Browser — Convert DRM-free EPUB ebooks to clean, formatted A4 PDF documents directly in your browser. Preserves typography, chapter images, and book spine order locally.
• Free Online PDF Merger - Combine PDF Files In-Browser — Combine and reorder multiple PDF documents into a single contiguous file directly in your browser. Lossless vector quality, in-memory execution, and zero cloud uploads.
• Free UUID Generator & Decoder (v1, v4, v5, v7) — Generate cryptographically random, time-ordered, and deterministic UUIDs directly in your browser. Inspect and decode UUID timestamps locally.
• Markdown to PDF Converter - GFM to Printable Document — Convert GitHub Flavored Markdown (GFM) into clean, high-resolution A4 PDF documents directly in your browser with code blocks, tables, and typography controls.
• Rich Text to PDF Converter - Format-Preserving Document Export — Convert Word documents, Google Docs, or formatted rich text into high-quality A4 PDF files directly in your browser. Preserves formatting, colors, headings, and lists.
• Free Text to PDF Converter - Searchable & Selectable Text — Convert raw text and TXT files into searchable, selectable A4 PDF documents with native Cyrillic and Extended Latin font support directly in your browser.
• IP Tracker - What is my IP? — Instantly find out your public IP address, location, ISP, Autonomous System Number (ASN), and map coordinates. Track any IPv4 or IPv6 address for free.
• Free QR Code Generator - Customize URL, Text & Wi-Fi Codes — Generate high-resolution, custom QR codes for URLs, Wi-Fi networks, and text with configurable Reed-Solomon error correction and instant PNG/SVG vector export.
• Website Font Finder - Inspect Web Typography — Detect and inspect typography, font families, font weights, Google Fonts, and @font-face declarations loaded on any website.
• Emoji Detector API & Unicode Sanitization Tool — Scan, detect, and strip Unicode emojis from text payloads. High-performance browser utility and API pattern for NLP preprocessing and database encoding.
• Collapsible Admonitions in Markdown and MDX — Implement expandable and collapsible callout boxes in Markdown, MDX, and Docusaurus using native HTML5 details elements and styled admonitions.
• Schema Markup & JSON-LD Validator — Validate and visualize JSON-LD structured data on any webpage. Fix syntax errors and ensure your Rich Snippets are ready for Google Search and AI engines.
• Accessible Color Palette Generator & Contrast Checker — Generate 5-color palettes compliant with WCAG 2.1 Level AA and AAA standards. Test contrast ratios, inspect relative luminance, and export accessible design tokens.
• Free Online Image Color Picker - Pixel Color Inspector — Extract exact pixel colors from uploaded images or pasted screenshots in HEX, RGB, HSL, HWB, and CMYK. Features a 11x11 magnifying loupe and color history.
• Free Online Color Converter (RGB, HEX, HSL, HWB, CMYK) — Instantly convert colors between RGB, HEX, HSL, HWB, and CMYK with integrated WCAG 2.1 contrast calculations, tints and shades palettes, and CSS token export.
• JWT Secret Key Generator - High-Entropy Cryptographic Keys — Generate cryptographically secure secret keys for JWT authentication (HS256, HS384, HS512) with instant .env formatting and real-time entropy estimation.
• Strong Password Generator - Cryptographically Secure Passwords — Generate cryptographically secure passwords with granular character pool controls, real-time Shannon entropy ratings, and NIST SP 800-63B compliance.
• Free Online Barcode Generator (Code 128, EAN-13, UPC-A) — Generate standard 1D linear barcodes in Code 128, EAN-13, UPC-A, and Code 39 formats with instant high-resolution PNG download and cURL API support.
• YouTube Metadata Toolkit - Titles, Tags and Thumbnails — Extract video titles, descriptions, SEO tags, and maximum resolution (1080p HD) thumbnails from any YouTube video in real time.
• YouTube Shorts Downloader - Save Shorts Videos — Download YouTube Shorts videos in high-quality vertical MP4 format. Fast, free, zero watermark downloads for mobile, desktop, and tablets.
• Twitter and X Video Downloader — Download high-definition videos and animated GIFs from Twitter (X) posts by entering any public tweet link. Zero watermark, full-speed MP4 downloads.
• PasteDownloader - Clipboard Image Downloader — Download images directly from your clipboard by pressing Ctrl+V or Cmd+V. Free, 100% client-side web utility that exports clipboard bitmaps to PNG files.
• Image Compressor - Optimize PNG, JPEG & WebP Online — Compress JPEG, PNG, and WebP images locally in your browser with adjustable quality levels, real-time file size savings, and sovereign API support.
• AI Background Remover - Transparent PNG Cutout Generator — Remove backgrounds from photos, products, and graphics automatically with high-precision edge matting, instant transparent PNG downloads, and sovereign API support.
• Social Media and Instagram Image Resizer — Crop and resize images for Instagram feeds, stories, reels, square posts (1:1), portrait (4:5), and landscape formats without unwanted cropping.
• Multi-Engine Reverse Image Search Launcher — Search any image across Google Lens, Bing Visual Search, Yandex, TinEye, and Baidu in one click. Trace image sources, find high-res duplicates, and detect plagiarism.
• Image Comparison Slider Creator - Before & After Generator — Create interactive before-and-after image comparison sliders and side-by-side visual diffs directly in your browser with instant WebP/PNG export.
• AdSense Revenue Estimator - Calculate Website Ad Earnings — Estimate website Google AdSense earnings based on page views, category RPM, traffic geography, and commercial valuation multiples.
• AdSense Verification & Policy Checker — Check websites for Google AdSense implementation, publisher ID detection (ca-pub-), ads.txt verification, and automated ad code configuration.
• Bookmark & Link Health Checker — Validate lists of bookmarks, external links, and URLs in bulk for broken links (404), redirect loops, SSL certificate issues, and response latencies.
• Website Tech & Tracker Detector — Detect analytics scripts, marketing trackers, CMS platforms, CDNs, server headers, and JavaScript frontend frameworks on any website.
• Website Favicon and App Icon Checker — Inspect favicons, Apple touch icons, Android web app manifests, and SVG vector icons for any website in real time.
• Open Graph Checker: Social Meta Tag Inspector & Preview — Test and preview Open Graph metadata, Twitter cards, and social share snippets for any URL in real time. Validate OG tags for Facebook, LinkedIn, Discord, and X.
• MetaCard API - Dynamic Social Media Thumbnail & Open Graph Generator — Dynamic social card generation API for blogs and websites. Generate customized Open Graph and Twitter Card thumbnails via URL parameters with edge caching.
• Link Redirect Tracer - HTTP 301, 302, 307 & 308 Hop Inspector — Trace URL redirect paths step-by-step, inspect HTTP status codes (301, 302, 307, 308), uncover affiliate tracking parameters, and detect circular redirect loops.
• Domain Lookup - WHOIS, DNS Records & Registration Info — Look up WHOIS records, registration timelines, DNS configuration (A, AAAA, MX, NS, TXT), and ICANN status codes for any domain in real time.
• Online GZIP Compressor - In-Browser File Compression — Fast, zero-server file compression and decompression using the RFC 1952 GZIP algorithm directly in your browser with real-time compression ratio metrics.
• Random String Generator API & Mock Data Service — Fast, reliable HTTP API and live interactive playground to generate customizable random strings for test fixtures, mock data, and development placeholders.

Telegram Automation Bots​

Automated bots running on asynchronous Python backends, MTProto protocol wrappers, and in-memory media pipelines.

• Base64 Transform Bot — Telegram Developer CLI Utility — Stateless Python Telegram bot providing Base64 encoding and decoding, smart quote normalization, cURL-to-Python requests conversion, JSON pretty-printing, and YouTube metadata extraction.
• InstaResizerBot — Telegram Image Resizer for Instagram Aspect Ratios — Stateless Python Telegram bot using Pillow (PIL) and in-memory BytesIO streams to pad portrait and landscape photos with white, black, transparent, or Gaussian blur borders.
• Kick and Ban All Members Bot — Telegram Supergroup Purge Utility — High-throughput Telegram group moderation bot using hybrid Webhook dispatching, Pyrogram MTProto member streaming, 60-second temporary soft kicks, and FloodWait auto-recovery.
• Post from Telegram to WordPress — Automated CMS Publishing Bot — Event-driven Python Telegram-to-WordPress bridge that publishes channel messages, HTML formatting, and high-resolution photos directly to WordPress via the REST API.
• ResponseWithBarcodeBot — Telegram Code 128 Barcode Generator — Stateless Python Telegram bot that encodes ASCII text and URLs into high-density Code 128 PNG barcodes in memory using python-barcode and BytesIO streams.
• ResponseWithQrBot — Telegram In-Memory QR Code Generator — Stateless Python Telegram bot that converts text and URLs into crisp 512x512 QR code PNGs in memory using python-qrcode, Pillow BOX resampling, and BytesIO streams.

Browser Extensions​

Client-side automation and developer productivity extensions built for Chromium engines using Manifest V3.

• Delphi - PlayStation Store Price Tracker & Wishlist (Chrome Extension) — A Manifest V3 Chrome Extension and Side Panel companion to track PlayStation Store price drops across 50+ regions, predict seasonal sales cycles, and search live catalogs via GraphQL.
• Keep Scrolling - YouTube Shorts Auto-Scroller (Chrome Extension) — Automatically scrolls through YouTube Shorts with smart controls, sponsored ad skipping, comment drawer pause, 1x–3x loop multiplier, channel/title blacklist filtering, and background tab playback.
• Memory Crystal - Clipboard & Copy History (Chrome Extension) — A Manifest V3 Chrome Extension that preserves everything you copy as searchable Shards. Pin favorites, filter links and code snippets, and channel copies directly into active inputs.

Infrastructure & Communities​

Cloud architectures, dynamic DNS services, and developer engineering communities.

• Serhii Telegram Bots Empire - Suite Architecture & Directory — Technical architectural guide, engineering decisions, and complete directory of the Serhii Telegram Bots Empire ecosystem, built by Serhii Hrekov featuring specialized developer bots for data transformation, QR/barcode generation, media processing, and central hub management via @serhiixxxbot.
• Ddnames - Dynamic Domains for IoT Devices — A platform for managing dynamic domain names, tailored for IoT devices and personal infrastructure based on API, JSON, and PowerDNS.
• Serhii Talks - Centralized Content Persistence & Telegram Broadcast Architecture — Comprehensive technical architecture and implementation details of serhiiTalks, an automated content aggregation and database fallback pipeline built by Serhii Hrekov with Python, FastAPI, PostgreSQL (Neon), Celery, and Redis.

Technical Credentials & Contact​

• Resume & Experience: For detailed employment history, tech stack, and achievements, view my Resume or Download Resume (PDF).
• Background & Bio: Read about my engineering background on the About Page.
• Direct Contact: Connect on LinkedIn, GitHub, X, or message directly on Telegram.