Why I Built 17 Developer Tools with Client-Side Processing

Sunny Raj — Sun, 16 Nov 2025 11:12:30 +0000

Why I Built 17 Developer Tools with 100% Client-Side Processing

As developers, we all repeat the same small tasks every day:

Formatting JSON
Decoding JWTs
Converting timestamps
Generating UUIDs
Encoding/decoding Base64
Converting JSON ⇄ CSV ⇄ YAML
Comparing text or payloads

Every engineer does these dozens of times a week. But almost every online tool I used was:

❌ Slow
❌ Filled with ads
❌ Sending data to a backend
❌ Breaking for large inputs
❌ Over-designed or cluttered
❌ Missing simple features

And when dealing with production logs, JWT tokens, or internal API payloads, pasting data into random websites is a huge privacy risk.
That’s why I built HashCodeTools — a collection of 17 fast, minimal, privacy-focused developer utilities that run 100% in the browser.

👉 https://hashcodetools.com

No backend.
No tracking.
No analytics.
No data storage.
Everything stays in your browser.

What’s Inside HashCodeTools?

Today, the toolbox includes:

JSON Formatter & Validator
JWT Decoder
Base64 Encoder/Decoder
URL Encoder/Decoder
Epoch ↔ Human-Readable Converter
YAML ⇄ JSON Converter
CSV ⇄ JSON Converter
UUID Generator
QR Code Generator
Text Diff Viewer
HTML/CSS/JS Formatters
…and more utilities being added regularly.

Each tool is clean, instant, and built with the same principle:
Fast, local, reliable, and distraction-free.

Why client-side only?

Because developers deserve safe tools.
When you paste:
API logs from production
JWT access tokens
User data
Internal configs
Debug payloads
…into an online tool, you shouldn’t have to wonder:
“Is this being uploaded?”
“Is someone storing this?”
“Is this logged somewhere?”
“Is it being analyzed?”

With 100% client-side processing:
Everything happens in memory
Nothing is stored
Nothing is sent over the network
Nothing leaves your device

You could use these tools offline if you disable your internet — they still work.

Speed & Reliability

Most formatter or encoder websites slow down when you paste large JSON strings. Some freeze the browser completely.
I optimized each tool to:

Handle large payloads
Avoid blocking the UI thread
Use efficient parsing logic
Render results instantly
Use a clean UI with Monaco Editor
Minify unnecessary code
Developers like tools that simply work, without friction.

The real reason I built it

I’m a developer.
I build APIs.
I debug REST responses.
I inspect tokens.
I read logs.
I generate UUIDs.

I was building tools for myself first. Then I realized millions of developers are doing the same things every day. So instead of switching between 15 different websites, why not build:

👉 one clean toolbox
👉 one unified interface
👉 one privacy-safe place for everyday dev work

That’s how HashCodeTools was born.

Tech Stack

Next.js
TypeScript
Monaco Editor
TailwindCSS
Local-only logic (no APIs)
Vercel (for static hosting)

Every tool is built with modular components so I can scale it easily.

What’s next?

Chrome extensions for JSON Formatter & JWT Decoder
VSCode extension
More data formatting tools
Regex tester
GUID/ULID generators
Color utilities
Base64 → File converter
Open-source versions of each tool I want this to become the “developer Swiss Army Knife” — a place devs can bookmark and use 10–20 times a day.

Feedback welcome

If you try the tools, I’d love to know:
What tools should I add next?
What UI improvements do you want?
What performance issues you face?
Which tools you use most often?

Leave a comment — I’m actively building, improving, and expanding this.

##Try HashCodeTools
https://hashcodetools.com

A privacy-first toolbox for developers.
Made with ❤️ for the dev community.

DEV Community: Sunny Raj