DEV Community: Kalaivani R

Why Does This JSON Look Correct but Still Fail? (Most Developers Miss This)

Kalaivani R — Thu, 11 Jun 2026 20:45:11 +0000

Take a look at this JSON:

{
"name": "XYZ",
}

Can you spot the problem in 3 seconds?

Most developers don't.

At first glance, it looks perfectly fine. The brackets are there. The key is quoted. The value is quoted. The indentation looks clean.

Yet if you send this JSON to an API, parse it in JavaScript, or load it into most applications, it will fail immediately.

The culprit?

A single trailing comma.

{
"name": "XYZ"
}

This tiny difference is enough to make valid JSON become invalid JSON.

The Mistake Many Developers Make

When JSON fails, the first thing many developers do is open a JSON formatter.

The assumption is:

"If I format it, I'll find the problem."

Sometimes that works.

Most of the time, it doesn't.

Because a formatter and a validator solve completely different problems.

What a Formatter Actually Does

A JSON formatter only changes how JSON looks.

For example:

{"name":"XYZ","age":25,"city":"Chennai"}

can become:

{
"name": "XYZ",
"age": 25,
"city": "Chennai"
}

The data stays exactly the same.

The formatter simply makes it easier for humans to read.

That's all.

What a Validator Actually Does

A validator checks whether JSON follows the official JSON specification.

It looks for problems such as:

Missing commas
Trailing commas
Unclosed braces
Unclosed brackets
Invalid escape characters
Single quotes instead of double quotes
Missing quotation marks

A validator doesn't care whether your JSON is pretty.

It cares whether your JSON is correct.

Here's Where Developers Get Tricked

Consider these two examples.

Example 1
{"name":"XYZ","age":25}

Looks ugly.

But it's valid JSON.

Example 2
{
"name": "XYZ",
"age": 25,
}

Looks clean.

Looks professional.

Looks easier to read.

But it's invalid.

This is why formatting and validation are not the same thing.

A beautiful JSON document can still be broken.

Real-World Example

Imagine receiving a 2,000-line API response.

Everything appears properly indented.

Everything looks organized.

But somewhere deep inside the payload, one comma is missing.

Your formatter won't help.

Your validator will.

A good validator should tell you:

Exact line number
Exact column number
Error type
Suggested fix

Instead of forcing you to manually search through thousands of lines.

Why I Built Online JSON Tools

While working with APIs and backend integrations, I repeatedly ran into situations where JSON looked correct but wasn't actually valid.

TRY THIS :

Online JSON Formatter | Format, Validate & Beautify JSON

Format, validate, beautify, repair, compare, and convert JSON instantly with fast browser-based developer tools.

onlinejsontools.co.in

Many tools would simply display:

Invalid JSON

That's not very helpful.

I wanted a tool that could explain what was wrong and where the problem existed.

That's one reason I built Online JSON Tools.

The goal was to combine formatting and validation in a single workspace so developers can quickly identify issues without jumping between multiple tools.

The Takeaway

Here's a simple rule:

If JSON is hard to read, use a formatter.

If JSON won't parse, use a validator.

A formatter improves readability.

A validator ensures correctness.

And if your JSON "looks fine" but still fails, there's a good chance you're dealing with a validation problem rather than a formatting problem.

Sometimes the difference between working JSON and broken JSON is just a single character hiding in plain sight.

What's the longest time you've spent debugging a JSON error that turned out to be something ridiculously small?

Why I Built Online JSON Tools Instead of Another AI App

Kalaivani R — Thu, 11 Jun 2026 20:32:22 +0000

Everyone seems to be building AI products right now.

Open LinkedIn, Product Hunt, or Twitter, and you'll find hundreds of new AI tools launching every week. Most of them are built on top of existing AI models and compete in an increasingly crowded market.

When I started looking for my next side project, I asked myself a simple question:

Should I build another AI app, or should I solve a real problem that developers face every day?

I chose the second option.

That's how Online JSON Tools was born.

TRY THIS

Online JSON Formatter | Format, Validate & Beautify JSON

Format, validate, beautify, repair, compare, and convert JSON instantly with fast browser-based developer tools.

onlinejsontools.co.in

As a backend developer, I work with JSON constantly. API requests, API responses, configuration files, third-party integrations, log files, and microservices all rely heavily on JSON. On some days, I spend more time reading JSON than writing actual business logic.

Despite that, many online JSON tools felt outdated, cluttered, or incomplete.

Some had intrusive ads everywhere.

Some had poor dark mode support.

Some simply showed "Invalid JSON" without explaining what was actually wrong.

Others struggled with larger files or provided a poor editing experience.

I wanted something better.

So instead of building another AI wrapper, I decided to build a tool that developers could genuinely use every day.

The Goal

The goal was simple:

Create a fast, developer-focused JSON utility platform that prioritizes usability, performance, and clarity.

No unnecessary features.

No complicated setup.

No server dependency for basic operations.

Just a tool that helps developers work with JSON faster.

What the Tool Does

Currently, Online JSON Tools focuses on the most common JSON workflows:

Beautifying JSON
Minifying JSON
Validating JSON
Identifying syntax errors
Showing line and column information
Copying formatted output
Downloading processed JSON
Supporting dark mode for long development sessions

Everything happens directly in the browser.

Your JSON never needs to leave your machine for basic formatting and validation tasks.

One Problem I Wanted to Fix

Most validators stop at:

Invalid JSON

That message is technically correct.

But it doesn't help much.

Imagine opening a 500-line JSON document and being told only that it's invalid.

Now you have to search through the entire file trying to locate the issue yourself.

Instead, I wanted the validator to provide useful feedback:

Which line contains the error
Which column contains the error
What caused the problem
A suggested fix

Something as simple as a trailing comma can waste several minutes when you're dealing with large payloads.

Good tooling should reduce that friction.

Why Not Build an AI Product?

This was probably the biggest decision.

AI products are attractive because they are trending.

But trends change quickly.

Utility tools solve recurring problems.

Developers were formatting JSON ten years ago.

Developers are formatting JSON today.

Developers will probably still be formatting JSON ten years from now.

That makes the problem far more stable than chasing whatever technology trend happens to be popular this month.

I wanted to build something with long-term value rather than short-term hype.

Technical Decisions

I kept the initial architecture intentionally simple.

The platform is built using:

Next.js
TypeScript
Tailwind CSS
Monaco Editor

The first version is frontend-only.

That decision offers several advantages:

Faster deployment
Lower hosting costs
Better performance
Easier maintenance
No backend infrastructure

Since formatting and validation can happen entirely in the browser, there was no reason to introduce unnecessary complexity.

Sometimes the best architecture is the simplest one that solves the problem effectively.

Challenges During Development

What looked like a simple weekend project quickly became more complicated.

A JSON formatter sounds easy.

Paste JSON.

Call JSON.parse().

Display the result.

Done.

Reality was different.

I spent significant time improving the editing experience, handling validation errors properly, refining the interface, and making sure the tool behaved the way developers expect.

One of the most interesting challenges was making validation feedback useful instead of generic.

Another was ensuring the editor experience felt smooth and professional.

The goal wasn't just functionality.

The goal was usability.

What I Learned

Building developer tools taught me something important:

You don't need a revolutionary idea to create a useful product.

You don't need AI.

You don't need blockchain.

You don't need a complex SaaS platform.

Sometimes solving a small, annoying problem well is enough.

Developers appreciate tools that save time.

Even if that time savings is only a few minutes per day.

Those minutes add up.

What's Next?

Online JSON Tools is still growing.

Future improvements include:

JSON Diff Tool
JSON Tree Viewer
JSON Repair
JSON Escape and Unescape
Additional developer utilities

The vision is to create a practical toolkit that developers can rely on whenever they need to inspect, validate, transform, or analyze JSON.

Final Thoughts

Building another AI application would have been the obvious choice.

Building a JSON utility platform was the less exciting option.

But it was also the more practical one.

I developed Online JSON Tools because I wanted a faster and more developer-friendly way to work with JSON. Sometimes the best projects aren't the ones that follow the latest trend. They're the ones that solve a problem people already have.

If you're a developer, what JSON-related task do you find yourself doing most often?