JSON Formatter & Validator
Pretty-print and validate JSON
Browser-only processing
Related tools
More browser-based tools for this workflow.
What this tool does
Format, validate, and beautify JSON. Detects syntax errors with line numbers and helpful messages.
JSON Formatter & Validator is a free developer utility that gets the job done without installing software or creating an account. The whole process runs inside this browser tab, so your input never leaves your device. Common searches that land here include json pretty, web developer.
Key features
- Validates against the JSON spec with line/column-accurate error messages
- Pretty-prints with 2-space indent and minifies to a single line
- Handles multi-megabyte JSON smoothly without freezing the UI
- Copy or download the result instantly
Common use cases
- Inspecting API responses and webhook payloads
- Reformatting compacted JSON logs for debugging
- Validating config files before committing them
Things to know
- Strict JSON only — JSON5, trailing commas, and comments are rejected by design
Privacy & local processing
JSON Formatter & Validator processes everything inside your browser — your files and text are never uploaded to a server, never logged, and never shared with third parties.How to use JSON Formatter & Validator
- 01
Paste JSON.
- 02
Click Format.
- 03
Copy the pretty output.
Frequently asked questions
Is my data uploaded anywhere?
No. Every tool on WebToolsLabs runs entirely inside your browser. Your data never leaves your device.
Does it handle large files?
Yes — formatting runs locally and handles multi-megabyte JSON files smoothly in modern browsers.
Is this tool free?
Yes. All tools on WebToolsLabs are 100% free with no signup, no watermarks, and no usage limits.