33+ Free Developer Tools That Never Send Your Data

The Problem with Most Online Formatters You know the drill. You paste some JSON into a random online formatter, or convert a CSV to Markdown, or format a WeChat article. The tool works fine, but have you ever stopped to think about what happens to your data? Most "free" online tools send your content to their servers. Some store it. Some log it. Some sell aggregated data. You have no idea where your sensitive JSON payload, proprietary CSV data, or internal documentation ends up. The Client-Side Alternative I built tools.pixiaoli.cn — a collection of 33+ developer utilities that run entirely in your browser . No server uploads. No data collection. Your content never leaves your machine. What's Inside Here's a taste of what's available: JSON Formatter & Validator — Format, minify, validate, and tree-view JSON instantly CSV Converter — Convert between CSV, JSON, and Markdown tables WeChat Markdown Editor — Write Markdown and preview it exactly as it appears in WeChat articles Base64 Encoder/Decoder — With file upload support URL Encoder/Decoder — For query parameters and path segments Hash Generator — MD5, SHA-1, SHA-256, SHA-512 Color Converter — Between HEX, RGB, HSL, and named colors Regex Tester — Live pattern matching with highlighted results Diff Viewer — Side-by-side text comparison Code Formatter — JavaScript, CSS, HTML, SQL, and more UUID Generator — v4 UUIDs for APIs and databases QR Code Generator — Customizable with logo support Markdown Preview — Live split-pane editor Image Format Converter — PNG, WebP, JPEG, GIF, BMP, AVIF Text Case Converter — camelCase, snake_case, kebab-case, and more Lorem Ipsum Generator — Customizable paragraph count and word limits HTML Minifier — Remove whitespace and comments CSS Minifier — Compress stylesheets JavaScript Minifier — Obfuscate and compress JS XML Formatter — Pretty-print XML documents YAML Formatter — Validate and format YAML HTML to Markdown — Convert rich HTML to clean Markdown Markdown to HTML — Render Markdow