Is my JSON uploaded anywhere?

No. The formatter runs entirely client-side. Files never leave your browser unless you manually share or download them.

How large of a file can I format?

The in-browser editor comfortably handles files up to a few megabytes. For very large payloads consider streaming them in chunks.

What if the JSON is invalid?

The tool highlights the line and column of the first error so you can fix it quickly. Invalid input is never saved.

Is my JSON uploaded anywhere?

No. The formatter runs entirely client-side. Files never leave your browser unless you manually share or download them.

How large of a file can I format?

The in-browser editor comfortably handles files up to a few megabytes. For very large payloads consider streaming them in chunks.

What if the JSON is invalid?

The tool highlights the line and column of the first error so you can fix it quickly. Invalid input is never saved.

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Browser tool

JSON Formatter & Viewer

Format, validate, and explore JSON safely in your browser.

Format, validate, and troubleshoot JSON payloads with synchronized tree and code views. Enable persistence to store the last payload locally or copy the share link to reload the same state later.

Key points

Format or minify instantly

Clean up messy payloads with two-space indentation or compress them for transport. Validation catches syntax issues before you ship.

Tree and code views

Explore deeply nested objects with collapsible nodes or edit raw text. The views stay synchronized as you work.

Privacy by design

Everything runs in your browser. Optional persistence stores JSON locally with Dexie/localStorage so sensitive data never leaves your device.

Remember my last JSON on this device

Drag & drop JSON files here or click to browse

Supports JSON, NDJSON, and text files up to 5 MB.

Enable the advanced viewer on demand

We defer loading the 300 kB JSONEditor dependency until you ask for it. Enable the tree/code viewer when you need it to protect Core Web Vitals.

Preference is saved to this device for faster repeat visits.

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How to use this tool

Step 1
Paste or drop your JSON
Paste directly into the editor, drag a .json/.ndjson file, or reopen a saved share link with the ?data= parameter.
Step 2
Choose an action
Use Format for pretty output, Minify for compact payloads, or Validate to confirm the syntax before copying or downloading.
Step 3
Share or revisit later
Copy the share link to preserve state, enable persistence to store it locally, or download a JSON file for teammates.

Frequently asked questions

Is my JSON uploaded anywhere?: No. The formatter runs entirely client-side. Files never leave your browser unless you manually share or download them.
How large of a file can I format?: The in-browser editor comfortably handles files up to a few megabytes. For very large payloads consider streaming them in chunks.
What if the JSON is invalid?: The tool highlights the line and column of the first error so you can fix it quickly. Invalid input is never saved.

Avoid pasting production secrets or credentials. Persistence uses Dexie/localStorage within your browser and can be cleared at any time via the toggle above the editor.