Readable API responses
Pretty-print minified JSON to debug API responses or log output without switching editors.
JSON Toolkit
Format, compact, or validate JSON payloads.
Recent JSON runs
Run the formatter or validator to build a quick history you can reuse.
Result
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.
Use Cases
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.
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.
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.
Related Tools
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.