Introduction
Introduction How to Convert HEX, RGB, and HSL Colors and Check Contrast
Convert CSS color formats, adjust colors with HSL, and check foreground/background contrast for readable UI design.
Introduction How to Read a QR Code from an Image and Check the URL Before Opening It
Decode QR codes from images or screenshots, verify campaign links before printing, and inspect suspicious QR URLs safely.
Introduction How to Count Characters and Clean Text for Docs, Forms, and Code Snippets
Use character counts, line counts, whitespace cleanup, and HTML escaping to prepare text for documentation, metadata, forms, and development workflows.
Introduction How to Convert Milliseconds, Seconds, Minutes, and Hours for Timeouts and TTLs
Convert time units for API timeouts, cache TTLs, retry delays, polling intervals, and monitoring settings without mixing up milliseconds and seconds.
Use Case
Use Case Use a SQL formatter before review to make queries easier to read
A practical workflow for formatting long SQL queries so JOIN, WHERE, GROUP BY, and ORDER BY clauses are easier to review.
Use Case Visualize GitHub Actions needs dependencies with Mermaid
A practical workflow for reading complex GitHub Actions workflow YAML by separating job dependencies from step details.
Use Case Common pitfalls when drawing infrastructure diagrams with Mermaid
A practical guide to organizing node names, arrows, and diagram scope when building infrastructure diagrams with Mermaid in the browser.
Use Case Generate Mermaid ER diagrams from SQL DDL to review table relationships
A practical workflow for turning CREATE TABLE statements into Mermaid ER diagrams and checking foreign keys before a schema review.
Development Story
Development Story The 'Nobody Updated the Architecture Diagram' Problem
Ever felt that chill when someone asks 'Wait, isn't there another server in between?' This is the story of creating a real-time Mermaid infrastructure visualizer.
Development Story Losing My Mind in YAML Hell: Why I Built a CI/CD Visualizer
When the 'needs' dependencies in GitHub Actions became too chaotic for human eyes, I decided to turn the labyrinth of YAML into a clean flowchart.
Development Story Stop Crying Over JOINs: Behind the Visual SQL Builder
'Wait, how does a LEFT JOIN work again?' I built this no-code SQL tool so we can stop wasting hours debugging missing commas and syntax errors.
Development Story Solving JSON to TypeScript via Recursion: The Strength of Zero Dependencies
Generate type definitions instantly from API responses. A behind-the-scenes look at a lightweight, high-speed implementation using recursive algorithms.
Purpose of this site
We gather technical knowledge and handy tools in one place so developers can shorten research time and focus on implementation.
Who is it for?
For engineers, developers, and technical leads who want quick verification tools and practical reference material.
Why is it useful?
Articles and tools are paired so you can understand a topic, then immediately try it in the browser.
Privacy-conscious tools
Tool input is processed locally whenever possible, helping you work with development data more safely.
Tools
Development & DevOps
8 items
GitHub Actions Visualizer
Visualize and build GitHub Actions workflow YAML with interactive diagrams in the browser.
SQL Formatter
Format and beautify SQL queries for various dialects (MySQL, PostgreSQL, etc.) instantly.
Visual SQL Builder
Construct complex SQL queries with SELECT, JOIN, and WHERE clauses using an intuitive visual GUI.
SQL → ER Diagram
Parse CREATE TABLE statements and automatically generate ER diagrams with relationships for visualization.
Curl Converter
Convert cURL commands to code in Python, Node, Go, Rust, and more.
Chmod Calculator
Calculate and convert Linux file permissions between octal and symbolic formats with a visual UI.
Cron Editor & Parser
Parse Cron expressions into human-readable format and calculate next execution times for schedule verification.
Infrastructure Diagram Builder
Create system architecture and network diagrams with a GUI. Generate Mermaid code and images instantly.
Data Conversion & Schemas
6 items
JSON Formatter
Pretty-print or minify JSON for quick validation of payloads and logs.
JSON → TypeScript
Generate TypeScript interfaces from JSON instantly for API responses and configs, including optional/null hints.
JSON → Zod
Infer Zod schemas from sample JSON for parsing or runtime validation and share contracts quickly.
JSON → OpenAPI
Generate OpenAPI component schemas from example JSON in the browser to prep review-ready drafts.
JSON ⇔ YAML
Paste JSON or YAML and convert both ways with copy helpers for config or docs handoffs.
CSV ⇔ JSON Converter
Convert between CSV and JSON formats with support for custom delimiters and headers.
Security & Cryptography
5 items
Base64 / 58 / 32
Switch tabs to encode or decode with any base in one place while comparing lengths and URL safety.
JWT Tool
Create and decode HS256-signed tokens in the browser without sending keys out of your session.
Hash & HMAC Generator
Generate SHA-1, SHA-256, SHA-512 hashes and HMAC signatures instantly in the browser for secure data verification.
JWKS Generator
Build RSA key pairs, publish public JWKS, and sign RS256 JWTs locally to rehearse key rotation.
UUID Generator
Generate UUIDv4 identifiers and copy instantly for tests or collision checks.
Text & Code Helpers
4 items
Markdown Table Generator
Create and edit Markdown tables visually with CSV import/export and column alignment controls.
Text & Code Suite
Count text, escape HTML/XML, minify CSS/JS, and generate passwords for quick publishing checks.
Regex Tester
Validate patterns, flags, and captured groups in one view to mirror production-like tests.
Diff Viewer
Visualize text changes with inline highlighting to confirm edits before commits or reviews.
URL, QR & Network
4 items
URL Encode / Decode
Encode or decode URLs without leaving your browser to catch slug issues or encoding gaps.
URL Params → JSON
Turn query strings into JSON objects for quick inspection when debugging APIs or webhooks.
QR Generator
Turn any text or URL into a QR code and save as PNG for sharing Wi‑Fi setups or quick links.
QR Reader
Scan codes with the browser camera and decode locally without sending images to a server.
Design & UI
2 items
Date & Time
3 items
Time Zone Converter
Swap between any two time zones instantly (default UTC and JST) to sanity-check launch, meeting, or deploy times.
Time Units
Convert milliseconds through weeks at once and compare results for TTLs, delays, and retry windows.
UNIX Timestamp Converter
Convert UNIX timestamps (seconds or milliseconds) to UTC and local time instantly to validate logs and alerts.