I built JSON Viewer Pro — a fast, privacy-first JSON formatter/validator/minifier

I recently shipped JSON Viewer Pro: https://jsonviewerpro.com/

It’s a lightweight web tool to help with everyday JSON tasks:

• Format / pretty-print JSON
• Validate JSON (catch syntax errors)
• Minify JSON
• View JSON (read large nested objects easier)

The key goal was speed + privacy: JSON is processed in the browser so you don’t have to upload sensitive API responses to a server.

Why I built it

I frequently debug API responses and log payloads, and I found myself opening the same set of tools over and over:

• pretty print minified JSON
• check if JSON is valid
• minify JSON before sending/storing
• quickly inspect nested objects

So I built a clean, focused tool that I could improve over time.

What “privacy-first” means here

Many JSON samples contain:

• access tokens
• user emails / phone numbers
• internal IDs
• secrets embedded in config

For JSON Viewer Pro, the intention is:

• no login required
• no server-side processing for the core tools
• your JSON stays on your machine

(If I add cloud saving/sharing later, it will be opt-in and clearly separated from local tools.)

Tech stack

I started with a simple SPA idea, but then moved to Next.js App Router so that each tool can live on its own URL (better for SEO and indexing):

• Next.js (App Router)
• TypeScript
• Client-side JSON operations using JSON.parse() and JSON.stringify()
• Deployed on Vercel

Tool pages:

• JSON Formatter: https://jsonviewerpro.com/json-formatter
• JSON Validator: https://jsonviewerpro.com/json-validator
• JSON Minifier: https://jsonviewerpro.com/json-minifier
• JSON Viewer: https://jsonviewerpro.com/json-viewer

A small implementation detail (core idea)

Pretty-printing JSON is basically:

const obj = JSON.parse(input);
const formatted = JSON.stringify(obj, null, 2);

Minifying is:

const obj = JSON.parse(input);
const minified = JSON.stringify(obj);

Validation is the same parse step with friendly error handling.

The “hard” part isn’t the algorithm — it’s the UX:

• clear error messages
• copy/download convenience
• handling big JSON without freezing the UI
• a simple interface that stays out of the way

What’s next

I want to expand it carefully without turning it into a bloated app. Some ideas:

• Tree view improvements (expand/collapse, search, copy path)
• Diff view (compare two JSON blobs)
• Conversion tools (JSON ↔ YAML/CSV)
• Better error positioning (line/column hints)
• Optional offline/PWA mode

Try it + feedback

If you work with APIs, I’d love feedback on the UX and missing features:

👉 https://jsonviewerpro.com/

If you have feature requests, reply here — I’m iterating quickly.