About Our Developer Tools
Every ToolsFlash dev tool processes data locally with your browser's native engines — no server round-trips, no logging, no rate limits. That makes them safe for the things developers actually paste into tools: API responses with keys, JWT tokens, config secrets and brand colors.
What's in this category?
- JSON Formatter & Validator — beautify with 2/4-space or tab indentation, minify for production, and pinpoint syntax errors to the exact line and column.
- Base64 Encoder / Decoder — UTF-8 safe (emoji included) with a URL-safe variant for tokens and filenames.
- Color Picker & Converter — HEX ⇄ RGB ⇄ HSL live, plus a 9-step tint/shade scale and the complementary color, all copyable in one click.
- UUID & Lorem Ipsum Generator — bulk crypto-random UUID v4 (uppercase, no-dash and braces options) plus placeholder text by paragraphs, sentences or words.
- Markdown Previewer — live side-by-side Markdown → HTML with tables, fenced code, task lists and one-click Copy HTML.
- JWT Decoder & Inspector — decode header and payload, live expiry countdown, claim explanations and security warnings, without the token ever leaving your device.
- RegEx Tester & Debugger — live match highlighting, capture groups, replace preview and a plain-English pattern explainer (JavaScript flavor).
- Cron Expression Generator — build schedules visually, read them in plain English and preview the next 10 run times in your timezone.
- Hash Generator — SHA-256, SHA-512, SHA-1 and MD5 for text or files up to 200 MB, with instant checksum verification.
- CSV to JSON Converter — two-way CSV ⇄ JSON with RFC 4180 quoted-field parsing, delimiter auto-detection and type conversion.
- UTM Builder — assemble GA4-ready campaign URLs live with presets for Google Ads, Facebook and email, plus lowercase/space warnings and one-click copy.
- Meta Tag Previewer — see your Google snippet, Facebook and Twitter/X cards exactly as they'll render, with pixel-width warnings and paste-ready meta tags.
Comparing two payloads or configs? Our Text Diff Checker pairs perfectly with the JSON formatter.