Free Developer Tools

Everyday dev utilities that run 100% in your browser — safe for API keys, tokens and private payloads because nothing is ever uploaded.

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.

Comparing two payloads or configs? Our Text Diff Checker pairs perfectly with the JSON formatter.