{"slug": "10-free-developer-utility-tools-that-run-entirely-in-your-browser", "title": "10 Free Developer Utility Tools That Run Entirely in Your Browser", "summary": "A developer created 10 utility tools that run entirely in the browser, with all data processing occurring client-side and never sent to a server. Each tool is a single HTML file using vanilla JavaScript and browser APIs, hosted on GitHub Pages for free global access without server-side code or databases. The tools include JSON formatting, text diffing, UUID generation, QR code creation, and other common developer utilities, all working offline after initial load with no telemetry or analytics.", "body_md": "Every developer has a collection of bookmarklets and random websites they use for quick utilities: format some JSON, diff two configs, generate a UUID, encode something in base64.\n\nMost of these tools send your data to a server. I built **10 developer utility tools that never leave your browser.**\n\nEach tool is one HTML file. No React, no Vue, no build step. Vanilla JS + browser APIs:\n\nHosting: GitHub Pages (free, global CDN). No server-side code. No database.\n\nFormat, validate, minify JSON. Convert between JSON and CSV with smart type inference. Handles nested objects and big integers.\n\nCompare two texts side by side. Line-by-line and character-level diff using Longest Common Subsequence algorithm. Highlights insertions and deletions.\n\nEncode/decode text and files to/from Base64. Also includes hex and binary modes. File drag-and-drop support.\n\nGenerate UUID v4 (random) and v7 (time-ordered). Batch up to 100 at once. Uses crypto.getRandomValues() for true randomness.\n\ncrypto.getRandomValues() for secure randomness. Configurable length (8-128 chars), character sets, ambiguous character exclusion. Full entropy — no Math.random() shortcuts.\n\nGenerate QR codes for URLs, WiFi networks, email, SMS, and vCard contacts. Wraps qrcodejs library. Download as PNG.\n\nSplit-pane editor with live preview. GitHub-Flavored Markdown (tables, strikethrough, code blocks). Copy HTML or download.\n\nFull URL and component encoding. Data URL generation. Handles edge cases like nested encoding and special characters.\n\nHuman-readable dates to Unix timestamps (seconds and milliseconds) and vice versa. Timezone-aware ISO 8601 support. Relative time display.\n\nBinary, octal, decimal, hexadecimal. Fractional number support. Step-by-step conversion mode for learning.\n\n**Security.** Your JSON payloads, API keys, and configuration files never leave your device.\n\n**Offline.** All tools work without internet after first load. Service workers cache everything.\n\n**Speed.** No network round-trip. Type a UUID, get it instantly. Diff two files, see results immediately.\n\n**Auditable.** View source to confirm: no telemetry, no analytics, no hidden API calls.\n\nEvery tool works fully for free with reasonable limits. The PRO Bundle ($19.99 one-time) removes all limits across all tools with a single license key.\n\n*Part of 24 free browser tools — all client-side, no signup, no tracking.*\n\n*Previously: 7 PDF Tools | 5 Image Tools*", "url": "https://wpnews.pro/news/10-free-developer-utility-tools-that-run-entirely-in-your-browser", "canonical_source": "https://dev.to/xueboyang1985/10-free-developer-utility-tools-that-run-entirely-in-your-browser-bd1", "published_at": "2026-05-31 00:10:28+00:00", "updated_at": "2026-05-31 00:42:20.284978+00:00", "lang": "en", "topics": ["ai-tools"], "entities": ["GitHub Pages", "qrcodejs"], "alternates": {"html": "https://wpnews.pro/news/10-free-developer-utility-tools-that-run-entirely-in-your-browser", "markdown": "https://wpnews.pro/news/10-free-developer-utility-tools-that-run-entirely-in-your-browser.md", "text": "https://wpnews.pro/news/10-free-developer-utility-tools-that-run-entirely-in-your-browser.txt", "jsonld": "https://wpnews.pro/news/10-free-developer-utility-tools-that-run-entirely-in-your-browser.jsonld"}}