Overview

JSON Toolkit focuses on day-to-day JSON authoring tasks: make responses readable, ship compact payloads, confirm that incoming data is valid, and keep a reproducible context through the built-in local history.

How to Use

Select the operation
Choose pretty, compact, or validate depending on whether you want readability, smaller output, or confirmation.
Paste the JSON
Drop in any JSON string, object, or array. Validation runs strict parsing to catch trailing commas or invalid tokens.
Reuse the result
Review the byte-size summary and restore previous runs from history whenever you need the same payload again.

Use Cases

Readable API responses

Pretty-print minified JSON to debug API responses or log output without switching editors.

Trimmed payloads

Compact large objects before persisting them to storage or sending them over the network.

Validation checks

Verify JSON copied from documentation, customer input, or configs and surface syntax errors immediately.

Reusable workspaces

Use the built-in history to restore recently formatted payloads without hunting for previous snippets.

Frequently Asked Questions

Does validation support JSON5?

No. Validation follows the official JSON specification, so JSON5 features like comments or trailing commas will raise errors.

How is byte size calculated?

The tool uses UTF-8 byte length so the numbers match what would be transmitted over the network.

Concept Notes

Strict structure and hidden pitfalls

JSON forbids trailing commas and comments and requires double-quoted keys, so JavaScript object literals often fail when copied verbatim. Numbers are IEEE-754 doubles, meaning large integers (like IDs) can lose precision unless kept as strings, and missing fields are distinct from explicit null—important when validating payloads or evolving schemas safely.