--- title: "Portfolio | Jean Pierre Kolb" description: "Over 40 free browser-based developer tools, open-source projects on GitHub, and social media profiles by Jean Pierre Kolb." url: "https://www.jpkc.com/en/portfolio/" lang: "en" --- # Portfolio _Tools, open-source projects, and profiles_ ## **JPKCom** Developer Tools At [jpkc.com/tools/](https://www.jpkc.com/tools/) I provide a comprehensive collection of over 40 free, browser-based developer tools. The tech stack is built on PHP (PHP: Hypertext Preprocessor) 8.3, Bootstrap 5, jQuery 4, and modern JavaScript. All tools run entirely in the browser — no data is sent to any server. Processing happens exclusively on the client side, ensuring maximum privacy. Some tools require access to external resources for certain functions (e.g. DNS (Domain Name System) lookups, SSL (Secure Sockets Layer) certificate checks, SEO (Search Engine Optimization) analysis). For this purpose, I developed a dedicated proxy — see the [proxy section](#proxy) below. ### Code and Text - **[Beautify](https://www.jpkc.com/tools/beautify/)** — Format, beautify, and deobfuscate JavaScript, CSS (Cascading Style Sheets), and HTML (HyperText Markup Language) code. Make JSON (JavaScript Object Notation) and JSONP (JSON with Padding) readable. - **[Cheat Sheets](https://www.jpkc.com/tools/cheatsheet/)** — 220 cheat sheets for CLI (Command Line Interface) tools, package managers, and web development. Search commands and copy with one click. - **[Coder](https://www.jpkc.com/tools/coder/)** — Encode and decode HTML (HyperText Markup Language) entities, URL (Uniform Resource Locator)s, Base64, JSON (JavaScript Object Notation) strings, JWT (JSON Web Token), and Data URI (Uniform Resource Identifier)s. - **[Compiler](https://www.jpkc.com/tools/compiler/)** — Compile SASS (Syntactically Awesome Style Sheets)/SCSS (Sassy CSS) to CSS (Cascading Style Sheets), beautify and minify HTML (HyperText Markup Language), JavaScript, and CSS (Cascading Style Sheets). Split-view editors with upload and download. - **[Convertor PRO (Professional)](https://www.jpkc.com/tools/convertor/)** — Convert between HTML (HyperText Markup Language)/XML (Extensible Markup Language), JavaScript/CSS (Cascading Style Sheets) escapes, Unicode, UTF-8 (8-bit Unicode Transformation Format), UTF-16 (16-bit Unicode Transformation Format), hexadecimal, URI (Uniform Resource Identifier) encodings, and data formats (YAML (YAML Ain't Markup Language), JSON (JavaScript Object Notation), TOML (Tom's Obvious Minimal Language), XML (Extensible Markup Language)). - **[CSV (Comma-Separated Values) Editor](https://www.jpkc.com/tools/csv/)** — Open, edit, and export CSV (Comma-Separated Values) files online. Spreadsheet editor with automatic delimiter detection. - **[JSON (JavaScript Object Notation) Editor](https://www.jpkc.com/tools/json/)** — Modern JSON (JavaScript Object Notation) editor with tree, table, and code views. Format, validate, repair, and transform JSON (JavaScript Object Notation) data. - **[Lorem Ipsum](https://www.jpkc.com/tools/lorem-ipsum/)** — Generate placeholder text in Latin, English, or German. Choose length by paragraphs, words, or characters. - **[Markdown Editor](https://www.jpkc.com/tools/md/)** — Write Markdown with live preview, synchronized scrolling, GitHub Flavored Markdown support, and HTML (HyperText Markup Language) export. - **[Playground](https://www.jpkc.com/tools/playground/)** — Interactive HTML (HyperText Markup Language), CSS (Cascading Style Sheets)/SCSS (Sassy CSS), and JavaScript editor with live preview, Bootstrap/jQuery assets, and save slots. - **[Regex Debugger](https://www.jpkc.com/tools/regex/)** — Test and debug regular expressions with real-time matching, flag support, and an integrated cheat sheet. - **[Source Viewer](https://www.jpkc.com/tools/source/)** — Code editor with syntax highlighting for 100+ languages, code beautification, URL (Uniform Resource Locator) loading, and HTML (HyperText Markup Language)-to-Markdown conversion. - **[WP (WordPress) Code Generator](https://www.jpkc.com/tools/wp/)** — Generate WordPress boilerplate code for plugins, themes, blocks, hooks, CPTs (Custom Post Types), taxonomies, meta fields, and settings pages. - **[WYSIWYG (What You See Is What You Get) Editor](https://www.jpkc.com/tools/wysiwyg/)** — Rich text editor based on TipTap with Markdown import/export, syntax highlighting, and HTML (HyperText Markup Language)5 local storage. Create and edit HTML (HyperText Markup Language) content visually in the browser. ### Design and Graphics - **[Colors](https://www.jpkc.com/tools/colors/)** — Color toolkit for web developers: color picker, gradient generator, CSS (Cascading Style Sheets) box-shadow and shadow-gradient builders, image palette extractor. - **[Fonts](https://www.jpkc.com/tools/fonts/)** — Preview and compare base fonts, Google Fonts, and custom font files in real time with adjustable size and weight. - **[GeoPattern](https://www.jpkc.com/tools/geopattern/)** — Generate beautiful geometric SVG (Scalable Vector Graphics) patterns from any text string. - **[Graphic Editor](https://www.jpkc.com/tools/graphic/)** — HTML (HyperText Markup Language)5 image editor for cropping, scaling, and format conversion. Export to PNG (Portable Network Graphics), JPEG (Joint Photographic Experts Group), WebP (Web Picture), and AVIF (AV1 Image File Format). - **[PDF (Portable Document Format) Tools](https://www.jpkc.com/tools/pdf/)** — Create, view, edit, merge, and split PDF (Portable Document Format) files in the browser. Annotate, highlight, draw, and extract text. - **[Periodic Table (PSE (Periodic System of Elements))](https://www.jpkc.com/tools/pse/)** — Interactive periodic table of all 118 elements with category filter, search, and detailed element data. - **[Placeholder Generator](https://www.jpkc.com/tools/ph/)** — Generate custom placeholder images with configurable dimensions, colors, and text. Presets for social media and web banners. - **[Trianglify UI (User Interface)](https://www.jpkc.com/tools/trianglify/)** — Generate algorithmically created low-poly triangle background patterns with customizable colors and complexity. ### AI (Artificial Intelligence) and SEO (Search Engine Optimization) - **[llms.txt Generator](https://www.jpkc.com/tools/llms/)** — Generate and validate llms.txt files for websites. A live checker fetches an existing llms.txt from any URL (Uniform Resource Locator) and validates it. The proposed standard helps AI (Artificial Intelligence) language models understand web content. - **[Meta Tags Generator](https://www.jpkc.com/tools/meta-tags/)** — Generate meta tags: Open Graph, Twitter/X Cards, mobile, security, performance, and structured data (JSON-LD (JavaScript Object Notation for Linked Data)) with live preview. - **[robots.txt and Sitemap](https://www.jpkc.com/tools/robots-sitemap/)** — Generate robots.txt (with user-agent rules, AI (Artificial Intelligence) bot blocking) and sitemap.xml. Additional live checkers fetch and validate robots.txt and sitemap.xml from any URL (Uniform Resource Locator). - **[SEO (Search Engine Optimization) and GEO (Generative Engine Optimization) Analyzer](https://www.jpkc.com/tools/seo/)** — Comprehensive SEO (Search Engine Optimization) and GEO (Generative Engine Optimization) analysis: HTTP (Hypertext Transfer Protocol) headers, SSL (Secure Sockets Layer) certificates, redirect chains, meta tags, links, images, structured data, accessibility, robots.txt, and AI (Artificial Intelligence) readiness scoring. ### Security and Utilities - **[Cryptor](https://www.jpkc.com/tools/cryptor/)** — AES (Advanced Encryption Standard)-256-bit encryption and decryption of text messages. Client-side encryption with password protection. - **[DNS (Domain Name System), SSL (Secure Sockets Layer), Redirect, and URL (Uniform Resource Locator)](https://www.jpkc.com/tools/dns-ssl-redirect-url/)** — Check DNS (Domain Name System) records (incl. DKIM (DomainKeys Identified Mail)), analyze SSL (Secure Sockets Layer) certificates, trace HTTP (Hypertext Transfer Protocol) redirects, parse URL (Uniform Resource Locator)s, and generate SPF (Sender Policy Framework) records. - **[Cron Job Helper](https://www.jpkc.com/tools/cron/)** — Visual cron expression builder with presets and next-run preview. Setup guides for WordPress, TYPO3, Drupal, Laravel, Docker, and DDEV (DDEV Local Development Environment). - **[Docker/Podman Composer](https://www.jpkc.com/tools/docker/)** — Convert `docker run` and `podman run` commands to Docker Compose YAML (YAML Ain't Markup Language) and back. - **[IP (Internet Protocol) Tools](https://www.jpkc.com/tools/ip/)** — IPv4 and IPv6 utilities: detect your IP (Internet Protocol), calculate subnets, convert IP (Internet Protocol) formats, generate IPv6 ULA (Unique Local Address) prefixes. - **[Generator](https://www.jpkc.com/tools/generator/)** — Generate passwords, salt and security keys, BCrypt/Argon2 hashes, and TOTP (Time-based One-Time Password) one-time passwords with QR code. - **[Hash Generator](https://www.jpkc.com/tools/hash/)** — Generate MD5, SHA-1, SHA-256, SHA-384, SHA-512, SHA-3, and RIPEMD-160 hashes with HMAC (Hash-based Message Authentication Code) support. - **[Info Tools](https://www.jpkc.com/tools/info/)** — Display browser information, HTTP (Hypertext Transfer Protocol) headers, IP (Internet Protocol) address, installed plugins, and HTML (HyperText Markup Language)5/CSS (Cascading Style Sheets)3 capabilities. - **[Mail Header Analyzer](https://www.jpkc.com/tools/mail-header/)** — Parse and visualize email headers (RFC (Request for Comments) 5322). Trace delivery routes and check SPF (Sender Policy Framework)/DKIM (DomainKeys Identified Mail)/DMARC (Domain-based Message Authentication, Reporting and Conformance) authentication. - **[PKI (Public Key Infrastructure) Viewer](https://www.jpkc.com/tools/pki/)** — Inspect X.509 certificates, PKCS#7/P7M, PKCS#12/PFX, CSR (Certificate Signing Request), and keys. View details, check validity, and extract P7M content. - **[SSH (Secure Shell) Proxy](https://www.jpkc.com/tools/ssh-proxy/)** — Generate SSH (Secure Shell) tunnel, SOCKS (Socket Secure) proxy, and port forwarding commands. Configurations and guides for Linux, macOS, Windows, BSD (Berkeley Software Distribution), and WSL (Windows Subsystem for Linux). - **[QR Code Generator](https://www.jpkc.com/tools/qr/)** — Generate styled QR codes from text, URL (Uniform Resource Locator)s, Wi-Fi credentials, vCard contact data, and more — with custom dot and corner styles, color gradients, a center logo, adjustable size and error correction, plus export to SVG (Scalable Vector Graphics), PNG (Portable Network Graphics), JPEG (Joint Photographic Experts Group), and WebP (Web Picture). - **[Time Converter](https://www.jpkc.com/tools/time/)** — View international time formats and convert Unix timestamps to human-readable dates and vice versa. - **[UUID (Universally Unique Identifier) Generator](https://www.jpkc.com/tools/uuid/)** — Generate RFC (Request for Comments) 4122 compliant UUID (Universally Unique Identifier)s in various formats. --- ## Localproxy — Proxy for **JPKCom** Developer Tools Some of the tools listed above require access to external resources, e.g. for DNS (Domain Name System) lookups, SSL (Secure Sockets Layer) certificate checks, or SEO (Search Engine Optimization) analysis. Browser security policies (CORS (Cross-Origin Resource Sharing)) normally prevent such access. For this purpose, I wrote a lightweight HTTP (Hypertext Transfer Protocol) proxy in pure Go — no external dependencies, single-file architecture (`main.go`): **[github.com/JPKCom/proxy-jpkcom-dev-tools](https://github.com/JPKCom/proxy-jpkcom-dev-tools)** - **How it works** — The proxy runs as a standalone binary on your machine and binds exclusively to `127.0.0.1`. All requests require per-session token authentication via the `X-Proxy-Token` header. Built-in SSRF (Server-Side Request Forgery) protection prevents access to private IP (Internet Protocol) ranges through DNS (Domain Name System) resolution checks. - **Endpoints** — `/proxy` — Forward HTTP (Hypertext Transfer Protocol)/HTTPS (Hypertext Transfer Protocol Secure) requests with streaming body support `/inspect` — Return connection metadata as JSON (JavaScript Object Notation): SSL (Secure Sockets Layer) certificate chains, TLS (Transport Layer Security) versions, IP (Internet Protocol) addresses, headers, and millisecond-precision connection profiling (DNS (Domain Name System) lookup, TCP (Transmission Control Protocol) connect, TLS (Transport Layer Security) handshake, TTFB (Time to First Byte)) `/page` — Comprehensive page analysis in a single request: follows redirect chains server-side with per-hop metadata (timing, IP (Internet Protocol), headers), delivers SSL (Secure Sockets Layer) details, body content, and performance timing `/ping` and `/version` — Health checks and version information - **Security and configuration** — Configurable origin filtering for production use, configurable DNS (Domain Name System) servers (defaults to Cloudflare and Google), adjustable timeout and response size limits (default: 50 MB (Megabytes)). Categorized JSON (JavaScript Object Notation) error responses for different failure types (DNS (Domain Name System), TLS (Transport Layer Security), connection, timeout). - **Privacy** — By running locally on `127.0.0.1`, no data leaves your machine through third parties. The proxy acts as a direct intermediary between your browser and the target server — without external cloud services or intermediate servers. - **Platforms** — Linux, macOS, Windows, and BSD (Berkeley Software Distribution) variants - **General purpose** — Although the proxy was developed for the **JPKCom** Developer Tools, it is universally usable — wherever you need a local, authenticated HTTP (Hypertext Transfer Protocol) proxy with SSL (Secure Sockets Layer) inspection and connection profiling. --- ## **JPKCom** DB — Knowledge Base, Blog, and Docs At [jpkc.com/db/](https://www.jpkc.com/db/) I run **JPKCom** DB — a standalone, bilingual (English and German) knowledge base that combines blog, documentation, and knowledge base. It focuses on web development, servers, DevOps, security, as well as AI (Artificial Intelligence), SEO (Search Engine Optimization), and GEO (Generative Engine Optimization). Every page is additionally available as native Markdown so that AI (Artificial Intelligence) systems can read the data directly and without noise. A site-wide full-text search (Pagefind) opens up all areas. Technically, the site is built on Eleventy and Tailwind CSS (Cascading Style Sheets). - **[Blog](https://www.jpkc.com/db/en/blog/)** — Articles on web development, AI (Artificial Intelligence), and digital practice — starting with a series on SEO (Search Engine Optimization) and GEO (Generative Engine Optimization). - **[Cheat Sheets](https://www.jpkc.com/db/en/cheatsheets/)** — Over 200 command-line references, editorially prepared as in-depth articles and copyable with one click. - **[Tools documentation](https://www.jpkc.com/db/en/tools/)** — Comprehensive companion docs for the free **JPKCom** Developer Tools: overview, manual, examples, plus tips and tricks. - **[Guides](https://www.jpkc.com/db/en/guides/)** — Hands-on guides to my open-source projects, each cross-linked to the changelog. - **[Changelog](https://www.jpkc.com/db/en/changelog/)** — Version histories of the **JPKCom** projects, taken directly from each README. --- ## GitHub Repositories A selection of my open-source projects on GitHub, sorted by category. You can find my full profile at: **[github.com/JPKCom](https://github.com/JPKCom)** ### Proxy - **[proxy-jpkcom-dev-tools](https://github.com/JPKCom/proxy-jpkcom-dev-tools)** — Local HTTP (Hypertext Transfer Protocol) proxy written in Go for browser-based developer tools. Enables DNS (Domain Name System) lookups, SSL (Secure Sockets Layer) analysis, and page inspection while bypassing CORS (Cross-Origin Resource Sharing) restrictions. See [details above](#proxy). ### WordPress Plugins — Content and Display All plugins require PHP (PHP: Hypertext Preprocessor) 8.3+ and WordPress 6.9+, use strict typing, and are updated via automatic GitHub-based updates with SHA256 checksum verification. - **[jpkcom-post-filter](https://github.com/JPKCom/jpkcom-post-filter)** — Faceted navigation and filtering of posts, pages, and custom post types via WordPress taxonomies. SEO (Search Engine Optimization)-friendly URL (Uniform Resource Locator)s with filter state in the path, AJAX (Asynchronous JavaScript and XML) filtering with `history.pushState` and no-JS fallback. Four filter layouts (horizontal bar, columns, sidebar, dropdown), three list layouts (cards, rows, minimal). Native Gutenberg blocks, Elementor widgets, and Oxygen Builder elements. Four-tier caching (object cache, transients, APCu, PHP (PHP: Hypertext Preprocessor) file cache). Full accessibility with `aria-live` regions and `aria-pressed` toggles. No dependencies — no ACF (Advanced Custom Fields), Bootstrap, or jQuery required. - **[jpkcom-acf-jobs](https://github.com/JPKCom/jpkcom-acf-jobs)** — Job listing and application management plugin for ACF (Advanced Custom Fields) Pro. Three custom post types (jobs, locations, companies) with hierarchical organization. Flexible job types (full-time, part-time, contract, internship). Schema.org JobPosting integration for Google for Jobs. WPML (WordPress Multilingual Plugin) support, template override system, and Bootstrap 5 compatible. - **[jpkcom-acf-references](https://github.com/JPKCom/jpkcom-acf-references)** — Reference gallery plugin for ACF (Advanced Custom Fields) Pro with interactive client-side filtering and animated transitions. Three custom post types (references, locations, customers). Image gallery with lightbox modal and keyboard navigation. Multiple layout options (list, card grid, image overlay). WPML (WordPress Multilingual Plugin) support, `prefers-reduced-motion` compatible, and Bootstrap 5 compatible. - **[jpkcom-simple-lang](https://github.com/JPKCom/jpkcom-simple-lang)** — Lightweight per-post language selection that overrides the sitewide language setting in the frontend. Uses the WordPress core language system, automatically updates the HTML (HyperText Markup Language) `lang` attribute, generates `hreflang` meta tags for SEO (Search Engine Optimization). Compatible with Yoast, Rank Math, and Oxygen Builder. Multisite support. - **[jpkcom-fa-svg-plugin](https://github.com/JPKCom/jpkcom-fa-svg-plugin)** — Shortcode plugin for embedding Font Awesome Pro (v5.15.4) as inline SVG (Scalable Vector Graphics). Supports all icon types (solid, light, regular, duotone, brands), CSS (Cascading Style Sheets) classes, styles, and `title`/ARIA (Accessible Rich Internet Applications) labels for accessibility. Works in menus, Gutenberg, and via `do_shortcode()`. Multisite support. - **[jpkcom-gutenberg-img-alt](https://github.com/JPKCom/jpkcom-gutenberg-img-alt)** — Automatically syncs image alt attributes in the Gutenberg block editor with media library metadata. Dynamic updates via regex — ensures alt texts stay current even when changed in the media library after insertion. Promotes SEO (Search Engine Optimization) and accessibility. - **[jpkcom-rank-math-options](https://github.com/JPKCom/jpkcom-rank-math-options)** — Companion plugin for Rank Math SEO (Search Engine Optimization): unlocks the `robots.txt` and `.htaccess` editors on multisite, removes the "Powered by Rank Math" notice from the frontend and XML (Extensible Markup Language) sitemap, forces anonymous telemetry off, cleans up the generated `llms.txt`, and hides the Rank Math admin bar menu. Network-ready, no configuration needed. ### WordPress Plugins — Security - **[jpkcom-hide-login](https://github.com/JPKCom/jpkcom-hide-login)** — Renames the default WordPress login URL (Uniform Resource Locator) (`wp-login.php`) to a custom slug. Built-in brute force protection with configurable thresholds (max attempts, time window, block duration). IP (Internet Protocol) whitelist with CIDR (Classless Inter-Domain Routing) support, WP-CLI (WordPress Command Line Interface) commands, and multisite support. WooCommerce compatible, REST (Representational State Transfer) API (Application Programming Interface) safe, no core file modifications. - **[jpkcom-disable-xmlrpc](https://github.com/JPKCom/jpkcom-disable-xmlrpc)** — Globally disables WordPress XML-RPC (Extensible Markup Language Remote Procedure Call): empties the method list via filter and blocks direct access to `xmlrpc.php` with a 403 error. Protects against automated attacks on the XML-RPC (Extensible Markup Language Remote Procedure Call) interface. - **[jpkcom-disable-comments](https://github.com/JPKCom/jpkcom-disable-comments)** — Completely disables WordPress comment functionality site-wide: removes UI (User Interface) elements from admin, menus, admin bar, and dashboard, disables trackbacks, empties comment arrays, and removes REST (Representational State Transfer) API (Application Programming Interface) comment endpoints. - **[jpkcom-argon2](https://github.com/JPKCom/jpkcom-argon2)** — Enables the ARGON2ID algorithm for all WordPress password hashes. Replaces the default hashing with the more modern and secure Argon2id algorithm. Multisite support, no configuration needed. --- ## Social Media Profiles - **[Mastodon](https://mastodon.social/@JPKCom)** — JPKCom@mastodon.social — Fediverse profile - **[GitHub](https://github.com/JPKCom)** — JPKCom@GitHub — Open-source projects and code repositories - **[GitLab](https://gitlab.com/JPKCom)** — JPKCom@GitLab — Additional code repositories - **[Drupal](https://www.drupal.org/u/jpkcom)** — JPKCom@Drupal — Drupal community profile - **[XING](https://www.xing.com/profile/JeanPierre_Kolb2)** — Business network profile - **[LinkedIn](https://de.linkedin.com/in/jpkcom)** — International business network profile - **[Google Business](https://goo.gl/maps/uG5J7RKh5ST2)** — Google business profile - **[Gravatar](https://gravatar.com/jpkcom)** — Global avatar and profile on WordPress/Gravatar --- ## Err-O-Rama Even error pages deserve some fun. Each HTTP (Hypertext Transfer Protocol) error page has its own theme, custom animations, and a few hidden details. - **[400 — Bad Request](/400.html)** — Glitch effect with RGB (Red Green Blue) split and animated interference bars - **[401 — Authorization Required](/401.html)** — Radar scanner with blips and status messages - **[403 — Forbidden](/403.html)** — Matrix rain with a playable Pong game - **[404 — Not Found](/404.html)** — The classic "page not found" page - **[405 — Method Not Allowed](/405.html)** — Padlock with key turn animation - **[408 — Request Timeout](/408.html)** — Hourglass with falling sand and countdown - **[410 — Gone](/410.html)** — Black hole with accretion disk and spiral vortices - **[418 — I'm a Teapot](/418.html)** — Hyperspace animation with a steaming teapot - **[429 — Too Many Requests](/429.html)** — Circuit board traces with overload effect - **[500 — Internal Server Error](/500.html)** — Kernel panic in terminal style - **[502 — Bad Gateway](/502.html)** — Bridge between client and server that collapses - **[503 — Service Unavailable](/503.html)** — Robot with wrench and spinning gears - **[504 — Gateway Timeout](/504.html)** — Clock with expiring countdown --- ## Logos and Graphics Graphics for download. - **** — 1260 × 1260 · 69 KB (Kilobyte) · `image/svg+xml` - **** — 2764 × 996 · 59 KB (Kilobyte) · `image/svg+xml` - **** — 410 × 410 · 1.6 KB (Kilobyte) · `image/svg+xml` - **** — 240 × 240 · 8.7 KB (Kilobyte) · `image/svg+xml` - **** — 1000 × 1000 · 9.5 KB (Kilobyte) · `image/svg+xml` - **** — 1024 × 1028 · 4.6 KB (Kilobyte) · `image/svg+xml` - **** — 1024 × 1024 · 958 KB (Kilobyte) · `image/png` ### Wallpaper Desktop wallpapers for download. - **[The Cube — Blue](/img/wallpaper/JPKCom-The-Cube-Blue-3200x2000.jpg)** — 3200 × 2000 · 298 KB (Kilobyte) · `image/jpeg` - **[The Cube — Gray](/img/wallpaper/JPKCom-The-Cube-Gray-3200x2000.jpg)** — 3200 × 2000 · 318 KB (Kilobyte) · `image/jpeg` - **[The Cube — White](/img/wallpaper/JPKCom-The-Cube-White-3200x2000.jpg)** — 3200 × 2000 · 360 KB (Kilobyte) · `image/jpeg` --- Have questions or feedback about any of these projects? [Get in touch](/en/imprint/).