I Built a Fast, Privacy-First JSON Formatter with Next.js

Lovlesh — Mon, 13 Jul 2026 00:33:01 +0000

As a developer, I work with JSON almost every day.

Whether it's debugging APIs, inspecting responses, or formatting configuration files, I constantly found myself opening online JSON formatter tools.

After trying dozens of them, I noticed a few recurring problems:

Some were cluttered with too many ads.
Some felt slow when formatting large JSON files.
Some uploaded data to a server, which isn't ideal when working with sensitive information.
Many had outdated interfaces and poor mobile support.

So I decided to build my own.

Goals

Before writing any code, I made a list of what I wanted:

I built the project using:

The goal wasn't just to create another JSON formatter—it was to build a growing collection of useful developer tools.

The formatter currently supports:

Since everything runs in the browser, your JSON stays on your device instead of being uploaded to a server.

One challenge was handling invalid JSON gracefully.

Instead of showing a generic error, I wanted the tool to clearly indicate when the JSON couldn't be parsed so developers could fix it quickly.

Performance was another focus. Large JSON files should still feel responsive without unnecessary loading.

This is only the beginning.

I'm planning to add many more developer tools, including:

The goal is to create a fast, simple collection of tools that developers can rely on every day.

If you'd like to try the formatter, you can find it here:

Thanks for reading, and happy coding!