DEV Community: Chhatrapal Singh

Stop pasting API responses into random JSON formatters

Chhatrapal Singh — Mon, 28 Sep 2026 09:49:18 +0000

Every day, developers paste production API responses, JWTs and config files into online JSON formatters. It's so routine that we rarely ask: where does that data go?

What many online tools do

Many popular formatters send your input to their server to process it. That means your JSON — customer records, emails, internal IDs, sometimes API keys — ends up in someone else's request logs.

You can check this yourself: open DevTools → Network, paste some JSON into a formatter, and watch for a POST request carrying your data.

JSON.parse silently changes your numbers

There's a second, subtler problem. Most browser-based formatters use JSON.parse, which converts numbers to JavaScript doubles:

JSON.parse('{"id": 9007199254740993}')
// → { id: 9007199254740992 }  ← off by one!

JSON.stringify(JSON.parse('{"price": 1.0}'))
// → {"price":1}               ← "1.0" became "1"

If your IDs are 64-bit integers (Twitter/X IDs, database keys, Snowflake IDs), a formatter built on JSON.parse can show you a different number than the one your API actually sent.

What a safe formatter should do

Process everything locally. No server round-trip at all.
Keep numbers exact. Use a parser that preserves the original text of each number.
Explain errors precisely. "Unexpected token" isn't enough — show the line, column and how to fix it.

What I built

I built JSON Formatter Kit with these rules in mind:

Everything runs in your browser — the site is static files, so there's no backend that could receive your data, and it works offline
A custom lossless parser, so 9007199254740993 and 1.0 stay exactly as written
Errors with line/column, a plain-English hint and one-click repair (trailing commas, single quotes, comments…)

It grew into 482 tools — converters, class generators, code formatters, hash generators, a JWT decoder and more — all following the same privacy rule.

Quick checklist for any online tool

Open DevTools → Network before pasting anything sensitive
Prefer tools that work offline (a good sign they don't need a server)
Never paste production secrets into a tool you can't verify

What tools do you trust with sensitive data? I'd love to hear in the comments.

# JSON Validation: Common Errors and How to Find Them

Chhatrapal Singh — Mon, 28 Sep 2026 09:48:09 +0000

A JSON response can look almost correct while still being invalid.

One small syntax mistake can prevent an API response, configuration file, or application from parsing correctly.

Let's look at some of the most common problems.

1. Missing Commas

This is invalid:

{
  "name": "John"
  "age": 30
}

There needs to be a comma between the properties:

{
  "name": "John",
  "age": 30
}

2. Using Single Quotes

JSON requires double quotes for strings.

Incorrect:

{
  'name': 'John'
}

Correct:

{
  "name": "John"
}

3. Trailing Commas

This is another common mistake:

{
  "name": "John",
  "age": 30,
}

Standard JSON does not allow the trailing comma.

4. Unclosed Brackets

Nested JSON makes this particularly easy to miss:

{
  "user": {
    "name": "John"
}

The nested object needs to be closed properly.

Why Validation Matters

When you're working with a large JSON document, manually finding these errors can be frustrating.

A JSON validator can quickly determine whether your document follows JSON syntax rules.

For quick validation, you can use:

https://jsonformatterkit.com/

JSON vs JavaScript Objects

It's also important to remember that JSON and JavaScript object syntax aren't exactly the same.

JavaScript may allow syntax that standard JSON does not.

For example:

const user = {
  name: "John"
};

JSON requires:

{
  "name": "John"
}

Conclusion

When JSON isn't parsing correctly, check:

Quotes
Commas
Brackets
Braces
Data types
Nested structures

A validator can save time when working with large or complicated JSON documents.

# How to Format JSON Properly: A Practical Guide for Developers

Chhatrapal Singh — Mon, 28 Sep 2026 09:21:32 +0000

JSON is one of the most common data formats used in modern web development. Whether you're working with REST APIs, configuration files, databases, or frontend applications, you'll eventually encounter JSON.

The problem is that JSON isn't always easy to read.

For example:

{"user":{"id":101,"name":"Alex","email":"alex@example.com","roles":["admin","developer"]}}

This is valid JSON, but reading nested objects in this format can be difficult.

What Does JSON Formatting Mean?

JSON formatting, also called JSON beautification, means adding indentation and line breaks to make the structure easier to understand.

The same JSON becomes:

{
  "user": {
    "id": 101,
    "name": "Alex",
    "email": "alex@example.com",
    "roles": [
      "admin",
      "developer"
    ]
  }
}

Now the hierarchy is immediately visible.

Why Is Formatting Useful?

Formatted JSON is particularly useful when:

Debugging API responses
Reviewing configuration files
Inspecting nested objects
Working with large API responses
Sharing JSON with teammates
Troubleshooting malformed data

Format JSON Directly in Your Browser

If you don't want to install a desktop application for a quick task, you can use a browser-based tool such as JSON Formatter Kit:

https://jsonformatterkit.com/

Paste your JSON, format it, and inspect the resulting structure.

Conclusion

JSON formatting doesn't change the underlying data. It simply makes the structure easier for humans to read and understand.

For developers who work with APIs regularly, keeping a JSON formatter available can save a surprising amount of time.

Why I Built JSON Formatter Kit: A Simple JSON Toolkit for Developers

Chhatrapal Singh — Mon, 28 Sep 2026 09:20:53 +0000

If you work with APIs, backend services, logs, or configuration files, you've probably dealt with JSON that looks like this:

{"user":{"id":123,"name":"John","roles":["admin","developer"],"settings":{"notifications":true,"theme":"dark"}}}

It's valid JSON, but it's not particularly pleasant to read.

Usually, the workflow is something like:

Copy the JSON.
Open a JSON formatter.
Paste it.
Format or validate it.
Copy the result back.
Repeat the process whenever you receive another response.

I wanted to make that workflow simpler, so I built JSON Formatter Kit.

What is JSON Formatter Kit?

JSON Formatter Kit is a browser-based collection of tools for developers working with JSON.

You can try it here:

https://jsonformatterkit.com/

The idea is simple: provide commonly needed JSON utilities in one place without requiring an installation or account.

JSON Formatting

One of the most common use cases is making minified JSON readable.

Instead of working with:

{"name":"John","age":30,"skills":["JavaScript","TypeScript","C#"]}

you can format it into something easier to inspect:

{
  "name": "John",
  "age": 30,
  "skills": [
    "JavaScript",
    "TypeScript",
    "C#"
  ]
}

This is especially useful when debugging API responses or inspecting data from browser DevTools.

JSON Validation

Another common problem is receiving JSON that doesn't parse.

A missing comma, extra quotation mark, or incorrect structure can make debugging surprisingly frustrating.

A JSON validator can quickly tell you whether the input is valid and help identify the problem.

JSON Beautifier and Minifier

Sometimes you need the opposite of formatting.

For development and debugging, pretty-printed JSON is much easier to read.

For certain production or data-transfer scenarios, minified JSON can reduce unnecessary whitespace.

So I wanted the toolkit to support both workflows.

Why Make Another JSON Tool?

There are already many great JSON tools available online.

I wasn't trying to reinvent JSON.

The goal was to build something:

Simple
Fast
Easy to use
Developer-focused
Accessible directly from the browser
Useful without installing software

There are also plenty of additional features that could be added in the future.

What's Next?

I'm considering adding more developer utilities based on actual developer workflows rather than simply adding tools for the sake of having more tools.

Some possible ideas include:

JSON comparison
JSONPath utilities
JSON ↔ CSV conversion
JSON ↔ YAML conversion
JSON schema utilities
API response inspection
More developer-focused formatting tools

I'd rather prioritize features people actually need.

I'd Love Your Feedback

If you work with JSON regularly, I'd be interested to hear:

What's the JSON-related task you find yourself doing repeatedly?

Is it formatting, validation, comparing API responses, converting formats, finding values inside large objects, or something else?

You can try the project here:

👉 https://jsonformatterkit.com/

If you have suggestions or find something that could be improved, I'd love to hear your feedback.

# I Built JSON Formatter Kit — A Free, Privacy-Focused Developer Toolkit

Chhatrapal Singh — Sat, 26 Sep 2026 10:17:49 +0000

If you've worked with APIs, backend development, configuration files, or debugging, you've probably had to deal with JSON that looks like this:

{"user":{"id":12345,"name":"John","email":"john@example.com","roles":["admin","developer"]},"active":true}

It's valid JSON, but it's not particularly pleasant to read.

Usually, the next step is opening a JSON formatter, copying the data, finding a validation tool, checking an error, and then switching to another website when you need to convert the data into another format.

I wanted to make that workflow simpler.

So I built JSON Formatter Kit — a free collection of browser-based tools for developers.

What is JSON Formatter Kit?

JSON Formatter Kit started with a simple idea:

Put the small developer utilities we use every day in one place.

The main tool is a JSON Formatter and Validator, but the project has grown into a broader developer toolkit.

The website currently includes tools for:

JSON formatting and validation
JSON viewing and exploration
JSON comparison and diff
JSONPath testing
JSON editing
JSON sorting
JSON ↔ CSV conversion
JSON ↔ XML conversion
JSON ↔ YAML conversion
JSON Schema generation
JSON → TypeScript
JSON → Python
JSON → Go
JSON ↔ Java
JavaScript formatting
TypeScript formatting
PHP formatting
Java formatting
GraphQL formatting
XML tools
YAML tools
HTML tools
CSS tools
Base64 encoding/decoding
URL encoding/decoding
HTML escaping
JWT decoding
UUID generation
Regex testing
Timestamp conversion
SQL formatting

There are currently 173 tools available across different categories.

Why another JSON formatter?

There are already plenty of JSON formatting websites.

So I wasn't trying to simply build another page with a textarea and a "Format" button.

I wanted to solve a few problems that I personally find annoying when using online developer tools.

1. Privacy

One of the biggest design decisions was to process data directly in the browser.

When you paste JSON into the formatter, parsing, validation, formatting, and tree visualization happen locally in your browser. The site states that the JSON isn't uploaded to a server.

This is particularly useful when working with:

API responses
Configuration files
Debugging data
Internal development data
Large JSON documents
Data that shouldn't be casually uploaded to third-party services

There is no requirement to create an account just to format JSON.

2. Better error messages

One of the most frustrating parts of working with JSON is finding out that something is invalid without knowing exactly what went wrong.

For example:

{
  "name": "John",
  "age": 30,
  "skills": ["C#", "JavaScript",]
}

The trailing comma makes this invalid JSON.

Instead of simply saying:

Invalid JSON

the formatter identifies the location of the syntax problem and provides an explanation and suggested fix.

The goal is to make the tool useful not only for formatting JSON, but also for debugging JSON.

3. Code view and tree view

Formatted JSON is useful, but sometimes you need to understand the structure of a large document.

JSON Formatter Kit provides a tree explorer where you can expand and collapse objects and arrays, search through keys and values, and inspect individual nodes.

You can also copy JSON paths and values from the tree.

For example, instead of searching through thousands of lines for:

customer.orders[12].items[3].price

you can navigate the structure visually.

4. Large JSON files

Another area I wanted to focus on was handling larger JSON documents.

The application uses background processing and virtualized rendering so that large documents don't require rendering everything into the page at once.

The current implementation supports files up to 200 MB per file, with the site noting that files in the tens-of-megabytes range work well on modern laptops.

That's useful when dealing with:

Large API responses
Exported datasets
Logs
Configuration dumps
Database exports

5. Preserving numbers and formatting

There is another subtle problem with JSON tools.

Consider a large integer:

{
  "id": 9223372036854775807
}

Depending on how a tool parses JSON, large numbers can potentially lose precision.

JSON Formatter Kit is designed to preserve numbers, decimals, and string escapes rather than silently rewriting them while formatting. According to the site's documentation, formatting changes whitespace rather than the underlying values.

That distinction matters when JSON contains IDs, financial values, timestamps, or other data where changing the representation could be problematic.

More Than a JSON Formatter

Although JSON is where the project started, I didn't want to stop there.

Developers constantly move between different formats.

For example, you might receive:

API → JSON → TypeScript interface

or:

JSON → CSV → Excel

or:

JSON → YAML → Configuration

Instead of searching for a different website every time, the goal of JSON Formatter Kit is to provide those utilities in one place.

JSON Converters

The site includes converters such as:

JSON to CSV
CSV to JSON
JSON to XML
XML to JSON
JSON to YAML
YAML to JSON

These are particularly useful when working with APIs, configuration files, data exports, and integrations.

Generate Code From JSON

Another category I'm particularly interested in is turning data into code.

For example, a JSON response can be used to generate structures for languages such as:

TypeScript
Python
Go
Java

There is also a JSON Schema generator.

This can save developers from manually creating models when working with API responses.

Developer Tools Beyond JSON

The project is gradually becoming a general-purpose developer toolkit.

There are tools for:

Code formatting

JavaScript
TypeScript
PHP
Java
GraphQL

XML

XML Formatter
XML Validator
XML Viewer
XML Minifier

YAML

YAML Formatter
YAML Validator
YAML Viewer

HTML

HTML Formatter
HTML Viewer
HTML Validator
HTML Minifier

CSS

CSS Beautifier
CSS Minifier
SCSS → CSS
CSS → SCSS

Encoding

Base64 Encode/Decode
URL Encode/Decode
HTML Escape
JSON Escape/Unescape

Developer utilities

JWT Decoder
UUID Generator
Regex Tester
Timestamp Converter
SQL Formatter

The idea is to make the site useful even when the task isn't specifically related to JSON.

Everything Runs in the Browser

One of the principles behind the project is:

If a tool doesn't need a server, don't use a server.

For many of these utilities, processing can happen entirely inside the browser.

That provides a few benefits:

No account required
No file upload required
Faster processing for many operations
Better privacy
Reduced server infrastructure
Tools can continue working offline after loading

For the main JSON formatter, the site specifically states that parsing, validation, formatting, and tree visualization happen in the browser.

A Small Example

Suppose an API returns:

{"id":1001,"name":"Alice","department":"Engineering","projects":[{"name":"API","status":"active"},{"name":"Dashboard","status":"completed"}]}

Instead of manually adding indentation, you can paste it into JSON Formatter Kit and get:

{
  "id": 1001,
  "name": "Alice",
  "department": "Engineering",
  "projects": [
    {
      "name": "API",
      "status": "active"
    },
    {
      "name": "Dashboard",
      "status": "completed"
    }
  ]
}

You can then switch to the tree view, search the document, copy values or paths, sort object keys, or download the formatted JSON.

Keyboard Shortcuts

For developers who prefer staying on the keyboard, the formatter also includes shortcuts.

For example:

Ctrl + Enter          Format JSON
Ctrl + Shift + Enter  Minify JSON
Ctrl + O              Open a file
Ctrl + S              Download output
Ctrl + Alt + C        Copy output
Ctrl + F              Search
Ctrl + Z              Undo
Alt + 1 / 2 / 3       Code / Tree / Stats

These are small features, but they make the tool much faster to use when you're working with JSON repeatedly.

What I'm Trying to Build

The long-term idea isn't just:

"another JSON formatter."

I want JSON Formatter Kit to become a developer toolbox that you can bookmark and return to whenever you need a quick utility.

Instead of searching:

JSON formatter
JSON validator
JSON to CSV
JWT decoder
UUID generator
Base64 decoder
Regex tester
SQL formatter
XML formatter

the idea is to have these utilities available from one place.

The focus is on making each tool:

Fast
Simple
Free
Privacy-friendly
Easy to understand
Useful without registration

What's Next?

The project is still evolving.

I'm continuing to improve existing tools, add new developer utilities, improve performance for large files, and make the overall experience better on desktop and mobile.

There are also plenty of possible tools I'd like to add based on what developers actually need.

If you use developer tools regularly, I'd love to hear what utilities you think should be included.

Maybe there's a small repetitive task you perform every day that could be turned into a simple browser tool.

Try It

If you work with JSON, APIs, configuration files, or other developer data, you can try the toolkit here:

👉 https://jsonformatterkit.com/

It's free to use, and the main JSON tools run directly in your browser.

If you try it, I'd be interested to hear what you think — especially which tools you find useful and what you'd like to see added next.

Built for developers, by developers — one small tool at a time.