JSON Formatter - Online JSON Validator & Pretty Print
Paste your JSON data to instantly format and beautify it with clean indentation. If a syntax error is detected, the exact line and column are highlighted automatically.
Beyond JSON formatting, the tool also supports minify mode, escape conversion, alphabetical key sorting, and Tree View visualization.
You can even convert JSON to XML or YAML in just one click.
Everything runs entirely in your browser. API responses and sensitive configuration files are never uploaded or stored on external servers.
Save frequently used JSON snippets to your favorites for quick access anytime.
It also works seamlessly with the URL Encoder & Decoder and Base64 Encoder for API debugging and data processing.
Real-Time JSON Validation & Scroll Sync
Working with large JSON files becomes frustrating when it’s difficult to locate syntax errors or compare the original and formatted output side by side.
Vivoldi JSON Formatter is designed to solve both problems at once.
Real-time JSON validation checks your input instantly as you type.
If an error occurs, the exact line and column are displayed immediately. Common mistakes such as trailing commas, single quotes, and mismatched brackets are easy to identify.
Scroll synchronization keeps both editors aligned automatically.
You can compare the original JSON and the formatted result at the same position, making even large API responses and configuration files much easier to review.
JSON Statistics, Favorites & Auto-Saved Settings
Vivoldi JSON Formatter includes several productivity features designed for developers who work with JSON every day.
Open JSON Statistics to instantly check file size (bytes), total key count, nesting depth, array count, object count, and root type.
It’s especially useful for analyzing API responses and understanding complex JSON structures.
With Favorites, you can save frequently used JSON snippets together with custom titles. All saved data stays only in your browser’s local storage and is never uploaded to external servers.
Editor preferences such as font size, tab width, and theme are saved automatically.
Even after refreshing the page, your previous settings remain exactly the same.
JSON Pretty Print Code Examples by Language
In real-world development, JSON often needs to be formatted directly inside code as well as through online tools.
Pretty-printed JSON improves readability when reviewing logs, debugging API responses, or saving configuration files. Below are common examples for popular programming languages.
| Language | Pretty Print Code | Indentation |
|---|---|---|
| JavaScript / Node.js | JSON.stringify(obj, null, 2) |
2 spaces (customizable) |
| Python | json.dumps(data, indent=4, ensure_ascii=False) |
4 spaces (Unicode supported) |
| Java (Jackson) | mapper.writerWithDefaultPrettyPrinter().writeValueAsString(obj) |
Jackson default |
| PHP | json_encode($data, JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE) |
4 spaces (Unicode supported) |
| Go | json.MarshalIndent(data, "", " ") |
2 spaces |
| C# | JsonSerializer.Serialize(obj, new JsonSerializerOptions { WriteIndented = true }) |
2 spaces |
| Ruby | JSON.pretty_generate(data) |
2 spaces |
You can paste formatted JSON from your code into this tool to inspect the structure visually, or copy formatted JSON from this tool directly into your application workflow.
JSON vs XML vs YAML - Which Format Should You Use?
JSON, XML, and YAML are all used to structure data, but each format is designed for different workflows and environments. If you’re unsure which one to choose, use the comparison below as a practical reference.
| Comparison | JSON | XML | YAML |
|---|---|---|---|
| Typical Use Cases | REST APIs, web apps, data exchange | Legacy systems, enterprise integrations, complex documents | CI/CD configs, Docker, Kubernetes |
| File Size | Lightweight | Larger because of repeated tags | Very lightweight |
| Readability | High (key-value structure) | Moderate (nested tags can become complex) | Very high (indentation-based) |
| Comment Support | Not officially supported | Supported | Supported (#) |
| Parsing Speed | Fast | Relatively slower | Moderate |
| Browser Support | Native support | Requires an additional parser | Requires an additional parser |
| Data Types | Supports numbers, booleans, and null | Mostly string-based | Supports numbers, booleans, and null |
JSON is the standard choice for REST APIs and modern web applications.
YAML is ideal for configuration files that developers edit manually. XML is still widely used in enterprise platforms and legacy system integrations.
With this formatter, you can instantly convert JSON into XML or YAML and compare the results side by side.
Explore JSON Structures with Tree View & Convert to XML or YAML
JSON files with deeply nested objects and arrays can be difficult to understand in plain text form.
Switch to Tree View mode to explore the hierarchy visually. Expand or collapse individual nodes and focus only on the sections you need.
Change the output format to XML or YAML to instantly convert the same data into a different structure directly in the right editor panel.
The converted result can be copied or downloaded as a file, making it easy to compare format differences using real-world data.
Open JSON Files, Load from URL & Edit in Fullscreen
Upload local .json files or enter an external URL to load JSON data directly into the editor.
Use it as a lightweight browser-based tool for opening and editing JSON files without installing additional software.
When working with large JSON datasets, fullscreen mode provides a much larger editing workspace.
Click the fullscreen icon in the top-right corner to expand the editor across the entire browser window.
Common JSON Syntax Errors and Their Causes
JSON uses strict syntax rules, so even a small mistake can cause parsing to fail. If an error message seems unclear, check the common issues below first.
Trailing commas are one of the most common JSON mistakes. If a comma remains after the last item in an array or object, the parser will throw an error.
The JSON specification does not allow trailing commas. This problem often appears when JavaScript object literals are copied directly into JSON.
Quotation marks are another frequent source of errors. Keys and string values must always use double quotes ("). Single quotes (') are not valid in standard JSON syntax.
Mismatched brackets and braces become harder to identify as nested structures grow more complex. Arrays must open and close with [], while objects must use matching {} pairs.
This formatter’s real-time validation highlights the exact line and column where the error occurs, helping you debug JSON much faster.
Frequently Asked Questions
Vivoldi JSON Formatter is an online tool that formats JSON into a clean, readable structure while detecting syntax errors in real time.
Main features include:
- JSON formatting and minify mode
- Real-time JSON validation — highlights the exact error line and column
- Scroll synchronization — both editors move together automatically
- Tree View — visualize nested JSON structures
- XML / YAML conversion
- Alphabetical key sorting — ascending, descending, or selected object range
- Escape character conversion
- Favorites storage — save up to 10 JSON snippets locally
- JSON statistics — file size, key count, nesting depth, and more
- Automatic editor settings save — preserved even after refreshing the page
No. All processing happens entirely inside your browser.
JSON containing API keys, passwords, or personal information is never transmitted externally.
Your input disappears when the page is closed. Data saved as favorites remains stored only in local storage.
When a JSON error occurs, the status bar at the bottom shows the exact line and column where the issue was detected. Go to that location and check the following items step by step.
- Check for trailing commas (
,) after the last element - Make sure keys and string values use double quotes (
") - Verify that arrays (
[]) and objects ({}) are correctly opened and closed - Check whether numbers, booleans, or null values are incorrectly wrapped in quotes
After making corrections, paste the JSON again and the validation results will update instantly in real time.
Files with the .json extension can be uploaded. Since all processing happens directly inside the browser, there are no separate server-side upload limits.
However, very large files may process more slowly depending on available browser memory and device performance.
When working with large JSON files, switching to fullscreen mode gives you a much larger editing workspace.
Select XML or YAML from the output format dropdown at the top of the right editor panel to instantly view the converted result.
The converted data can be used in several ways:
- Copy the result directly to your clipboard and paste it into your code
- Download the converted output as a file
- Compare structural differences between formats using real-world data
You can save up to 10 favorites. Each saved item can have a custom title for easier organization.
All saved data is stored only in your browser’s local storage.
Favorites are removed if you clear your browser data or manually delete individual items from the favorites list. They are not synced across different browsers or devices.
Yes. The Key Sorting feature lets you choose exactly which part of the JSON structure should be sorted using the Select Key dropdown.
- All Keys (Root Level) — sorts every key at the top level of the JSON object
- Select a specific object path — for example
useroruser.addressto sort keys only within nested objects
You can sort keys in ascending order (A → Z) or descending order (Z → A).