Introduction
Introduction How CREATE TABLE Generation From a Visual Table Design Works | DDL Builder
A look inside DDL Builder, which turns a visually designed table into CREATE TABLE statements and an ER diagram. Covers the MySQL/PostgreSQL/SQLite type-mapping rules and the column-inference algorithm used for JSON samples.
Introduction Case Converter: camelCase, snake_case & kebab-case — 9 Styles at Once
Convert identifiers between camelCase, PascalCase, snake_case, CONSTANT_CASE, kebab-case and more — all nine styles side by side. Handles acronym runs like HTTPServer, digits, and bulk multi-line conversion.
Introduction LLM API Cost Calculator: Compare Claude, GPT & Gemini Pricing Side by Side
Paste a prompt, set the expected output tokens, and compare per-request API costs across Claude, GPT and Gemini models. Covers input/output pricing structure, auto-updated price tables, and estimate limits.
Introduction AI Rules Generator: AGENTS.md, CLAUDE.md & Cursor Rules from One Form
Generate rules files for Claude Code, Cursor, GitHub Copilot, Windsurf and Gemini CLI in one shot. Covers the AGENTS.md standard, per-tool file formats, and why a single source of truth prevents rule drift.
Use Case
Use Case GitHub Actions needs Design Patterns: Speed Up CI, Avoid the Anti-Patterns
A pattern reference for GitHub Actions job dependencies (needs). Covers diamond-shaped fan-out, concurrency cancellation, fail-fast tradeoffs, matrix-plus-needs gotchas, and reusable workflows, with copy-paste YAML examples.
Use Case SQL JOIN Types: Complete Reference to INNER, LEFT, RIGHT & FULL
A reference for SQL JOIN types (INNER/LEFT/RIGHT/FULL/CROSS/SELF) with a cheat sheet and row-count walkthroughs. Covers why one-to-many joins duplicate rows, the WHERE-vs-ON NULL trap, and how to write multi-table joins.
Use Case AGENTS.md, CLAUDE.md, Cursor Rules: One Source of Truth for AI Coding Agents
Every AI coding agent wants its own rules file. Compare AGENTS.md, CLAUDE.md, .cursor/rules, copilot-instructions.md and more — what to write, a copy-paste template, and how to stop them drifting apart.
Use Case Mermaid ER Diagram Syntax Reference: Relationship Symbols & Real Examples
Complete reference for Mermaid erDiagram syntax: crow's foot cardinality cheat sheet, one-to-many vs many-to-many, attributes with PK/FK, and a full e-commerce example.
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
AI & LLM
3 items
Development & DevOps
9 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.
DDL Builder
Design tables and generate CREATE TABLE statements plus an ER diagram. Also infers columns from a JSON sample.
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
5 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.
Case Converter
Convert identifiers to camelCase, snake_case, kebab-case, and more at once.
URL, QR & Network
5 items
URL Encode / Decode
Encode or decode URLs without leaving your browser to catch slug issues or encoding gaps.
IP / CIDR Calculator
Compute the network, broadcast, host range, host count and masks from CIDR notation.
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.