UD5 Toolkit
Markdown Diff Viewer - Online Compare & Highlight Markdown
Paste two Markdown texts and see a side‑by‑side diff with rendered preview. Perfect for editing and collaboration.
Markdown Slide Deck - Online Presentation Builder
Markdown Editor
Use
--- to separate slides
Slide Preview
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Brick Breaker - Online Classic Breakout Arcade
Smash bricks with a ball and paddle. Multiple rows of colored bricks, power‑ups, and score tracking. All built with HTML5 Canvas.
Git Semver Tag Generator - Online Create Release Tags
Generate a series of semantic version tags with optional prefixes. Copy for your release script. Consistent tagging.
Paper Fold Simulator - Online Virtual Origami Practice
Fold a virtual square paper step by step with crease lines and visual previews. Practice origami basics without wasting real paper. All canvas‑based.
GraphQL Schema to Markdown Docs - Online Generator
Paste a GraphQL SDL schema and get auto‑generated Markdown documentation. Perfect for API docs. All local.
NPM Version Badge Generator - Online Shields Style
Pick a package name and generate a custom version or download badge as a static image or Markdown link. For readme files.
ZX Spectrum Basic Emulator - Online Retro Code Playground
Write and run simple Sinclair BASIC programs in a browser-based ZX Spectrum emulator. Load demo programs and experience 80s computing. Educational fun.
Random RSA/EC Key Pair Demo - Online Cryptographic Visualization
Generate a dummy RSA or EC public/private key pair for educational visualization. Shows key structure and ASN.1 dump. Not for production use.
Launch Handler API Demo - Online Control App Launch Behavior
Configure how your PWA launches: focus existing or create new. Test with the launch_handler manifest field.
JSON-LD Validator - Online Structured Data Syntax Checker
Paste JSON-LD and validate basic syntax and required properties for Article, Product, etc. Local only. Instant feedback.
Semantic Versioning Validator - Online Check Semver Syntax
Validate and compare semantic version strings. Check if a version satisfies a range (e.g., ^1.2.3). Visual breakdown of major.minor.patch. Local only.
Protocol Handler Registration - Online Register URL Scheme
Learn how to register your PWA to handle custom URL protocols. See the manifest entry and test.
PWA Manifest Generator - Online Create app.webmanifest
Fill in your PWA details to generate a valid manifest.json file. Include icons, theme color, display mode.
Swagger/OpenAPI YAML Previewer - Online Render & Test
Paste your Swagger/OpenAPI YAML and see a rendered API documentation preview with expandable endpoints. All local rendering.
PBKDF2 Key Derivation Demo - Online Password‑Based Key
Derive a strong cryptographic key from a password using PBKDF2 with SHA‑256. Adjust iterations and salt. Educational and test tool.
SQL Injection Simulator - Online Educational Sandbox
Test SQL injection inputs on a mock database and see the resulting query. Learn how to prevent SQLi. No real data.
Semantic Versioning Validator - Check Semver Syntax
Validate if a version string follows SemVer 2.0.0. Also sort and compare versions. Developer tool.
Trusted Types API Demo - Online Prevent XSS
See how Trusted Types prevents unsafe HTML assignment. Test against injected scripts. Modern security practice.
PWA Icon Resizer & Manifest - Online Generate Sizes
Upload a 512x512 logo and get resized icons for every PWA requirement. Download a zip and the corresponding manifest.json snippet.
GeoJSON Validator - Online Check Geometry & Properties
Paste a GeoJSON object and validate its structure. Catch missing coordinates, wrong types, and feature errors. Local.
Web App Manifest Validator - Online Check PWA Manifest
Paste your manifest.json and instantly validate it against the W3C spec. Catch errors and warnings. Client‑side.
Get Installed Related Apps Demo - Online PWA Detection
Check if your related native or PWA app is installed. See the API in action and copy the code.
.htaccess Validator - Online Check Syntax
Paste your .htaccess rules and check for common syntax errors or misconfigurations. No server required; static analysis.
YAML to JSON Converter - Online Config Translator
Translate YAML configuration files into JSON format instantly. Validate syntax during conversion. Perfect for DevOps and configuration management. Secure client-side operation.
CORS Proxy Emulator - Online Test Cross‑Origin Requests
Bypass CORS for testing by routing requests through a local service worker proxy. Debug APIs without server changes. Experimental.
XML to JSON Converter - Online Parse XML to Object
Parse XML strings into compact JSON representation. Handles attributes and text nodes intelligently. Quick and private, ideal for API response translation.
Speech Timer – Online Practice Presentations with WPM
Paste your speech, set time limit, and practice with a pacing indicator (words per minute). Refine delivery.
Markdown to PDF Converter - Online Export Clean Documents
Write Markdown and instantly print/save as a styled PDF. Choose from multiple themes. Uses browser print function for high-quality output. Local only.
Mermaid Diagram Renderer - Online Markdown to Chart
Write Mermaid syntax inside Markdown blocks and instantly see rendered flowcharts, sequence diagrams, and Gantt charts. Copy SVG.
Markdown Link Rewriter - Online Relativize or Absolutify URLs
Paste Markdown and convert all links from absolute to relative (or vice‑versa) based on a base domain. Bulk edit.