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Free Online Developer Tools: JSON Formatter, QR Code Generator, and More

Why Another Developer Toolbox?#

Every developer has been there: you need to quickly format some JSON, generate a QR code, or encode a string to Base64. You search, click the first result, and get hit with ads, cookie banners, and a signup wall — all for something that should take two seconds.

That’s why I built a set of free, no-nonsense browser tools that just work. No accounts, no tracking, no server-side processing. Everything runs in your browser.

The Tools#

JSON Formatter & Validator#

Try it →

Paste in messy JSON, get clean, syntax-highlighted output. It validates your JSON on the fly and shows clear error messages when something’s wrong. Supports minification too — handy when you need to stuff JSON into a config field or URL parameter.

Use cases:

  • Debugging API responses
  • Validating config files
  • Minifying JSON for production

Text Summarizer#

Try it →

Drop in a long article or document and get a concise summary. Powered by AI, running client-side. Great for quickly digesting lengthy documentation, meeting notes, or research papers without reading every word.

Use cases:

  • Summarizing documentation
  • Quick overview of long emails or reports
  • Condensing research notes

QR Code Generator#

Try it →

Type a URL, text, or any data — get a QR code instantly. Download it as PNG for presentations, business cards, flyers, or documentation. Customizable size, and the generation happens entirely in your browser.

Use cases:

  • Sharing URLs at presentations or meetups
  • Adding QR codes to printed materials
  • Quick device-to-device text transfer

Color Palette Generator#

Try it →

Generate harmonious color palettes for your next project. Extract colors, explore complementary schemes, and copy hex/RGB values with a click. Whether you’re designing a UI, picking a theme, or just exploring color combinations — this has you covered.

Use cases:

  • UI/UX design exploration
  • Finding complementary colors for branding
  • CSS theme generation

Base64 Encoder & Decoder#

Try it →

Encode text to Base64 or decode Base64 back to readable text. Simple, fast, and useful more often than you’d think — embedding images in CSS, decoding JWT payloads, working with APIs that use Base64 encoding.

Use cases:

  • Encoding/decoding JWT tokens
  • Data URI generation
  • Debugging encoded API payloads

Markdown to PDF Converter#

Try it →

Write or paste Markdown, get a clean PDF. Supports full GitHub-flavored Markdown — tables, code blocks, task lists, the works. Perfect for turning README files into shareable documents or converting notes into printable format.

Use cases:

  • Converting documentation to PDF for distribution
  • Creating printable reports from Markdown notes
  • Generating clean PDFs from README files

Why These Tools?#

A few principles behind the toolbox:

  1. Privacy first — Nothing leaves your browser. No data is sent to any server.
  2. No friction — No signup, no ads, no cookie consent popups. Open the link, use the tool.
  3. Fast — Static pages, minimal JavaScript. They load instantly.
  4. Free forever — These tools cost nothing to host and nothing to use.

The Full Toolbox#

All tools live at stevenli-phoenix.github.io/toolbox — bookmark it and you’ll always have them handy.

ToolLink
JSON Formattertoolbox/json.html
Text Summarizertoolbox/summarizer.html
QR Code Generatortoolbox/qrcode.html
Color Palettetoolbox/colors.html
Base64 Encodertoolbox/base64.html
MD to PDFmd2pdf

Support the Project#

If you find these tools useful, consider buying me a coffee — it helps keep the lights on and motivates me to build more free tools for the developer community.

Got a tool idea? I’m always looking for what to build next. Drop a suggestion on the Buy Me a Coffee page or open an issue on GitHub.


Happy coding!

Free Online Developer Tools: JSON Formatter, QR Code Generator, and More
https://blog.lishuyu.top/posts/free-developer-tools-toolbox/
作者
猫猫魔女
发布于
2026-03-29
许可协议
CC BY-NC-SA 4.0