JSON Formatter Online
Pretty-prints JSON in the browser and can show the same value as a collapsible tree. Paste JSON, format it with 2-space indent, or inspect keys. Parsing uses JSON.parse only. This is not a schema validator, and JSON is not executed.
JSON formatter online
Client-side only. JSON is not sent to a server. This is not a schema validator. JSON is not executed.
How to use
- Paste JSON in the box. Surrounding whitespace is allowed.
- Read the formatted JSON (2-space indent), or switch to Viewer for a collapsible tree of keys.
- Nothing is sent to a server. This is not a schema validator. JSON is not executed. Refreshing the page clears the form.
Results
Paste JSON to format or view.
Runs in your browser. Nothing is uploaded.
Frequently asked questions
What is the difference between Formatted and Viewer?
Formatted pretty-prints the JSON as text with 2-space indent. Viewer is a JSON viewer online on this same page: a collapsible tree of keys built from the parsed value. Both use the same JSON.parse result. Switch with the Formatted and Viewer controls.
How does this JSON formatter parse input?
It calls JSON.parse in your browser, then JSON.stringify(value, null, 2) for the formatted text. There is no Ajv, no schema download, and no server parser. Invalid JSON fails closed with an error. Trailing commas are invalid.
What indent does pretty-print use?
Pretty-print uses 2-space indent: JSON.stringify(value, null, 2). That is the only indent this page applies. Surrounding whitespace on valid JSON is allowed because JSON.parse already accepts it.
Are trailing commas allowed?
No. Standard JSON.parse rejects trailing commas. {"a":1,} and [1,] fail closed. Use strict JSON: double-quoted keys, no comments, no trailing commas.
Is there a size limit?
Yes. Input larger than 100KB (100 × 1024 UTF-8 bytes) is rejected. The limit counts the actual UTF-8 byte length of what you paste. Empty and whitespace-only input also fail closed. Nothing is sent to a server either way.
Is my JSON sent to a server?
No. Format and view run in your browser. The JSON never leaves the browser. There is no signup, and Tallymill does not save what you paste. Refreshing the page clears the form.
Is this a JSON schema validator?
No. This page formats and views JSON. It is not a schema validator, not Ajv, and not a JSON Schema checker. It does not fetch schemas and does not execute JSON. Keys are shown as text labels only.
Do I need an account? Does this run on the server?
No. The JSON formatter online (also a JSON viewer online on this same page) is client-side only. There is no signup. Nothing you paste is sent to a server. Refreshing the page clears the input.