JSON Validator
Check JSON for syntax errors and structural problems with clear, actionable messages. The validator helps you find and correct issues before they cause trouble in production.
JSON Validator
Validate JSON with precise error locations, friendly explanations, duplicate key detection, non-standard pattern warnings, and full structure analysis.
Paste JSON
Paste JSON above to validate it
Or load a valid or invalid sample to see it in action
Precise Error Location
When JSON is invalid, the validator shows the exact line and column number, highlights the context lines, and gives a human-friendly explanation of what went wrong.
Deep Structure Analysis
For valid JSON, get a full breakdown: key count, max nesting depth, top-level type, duplicate key detection, and a type distribution summary.
100% Private & Local
All validation runs in your browser using the native JSON.parse API. No JSON data is ever sent to a server or logged.
How to Validate JSON
Paste Your JSON
Copy any JSON string: from an API response, a config file, a log, or a code editor: and paste it into the input area.
See Instant Results
The validator parses your JSON immediately. A green badge confirms it's valid; a red badge pinpoints the exact error with context lines.
Explore the Structure
For valid JSON, expand the Structure Analysis panel to see key count, depth, type distribution, duplicate keys, and non-standard warnings.
Copy or Fix
Copy the raw JSON, switch to the JSON Formatter to pretty-print it, or fix the highlighted error and re-paste for instant re-validation.
Who Uses a JSON Validator?
Backend Developers
Validate API request and response bodies during development to catch malformed payloads before they reach production.
Frontend Developers
Check JSON config files, translation files, and package.json manifests for syntax errors before committing.
Data Engineers
Validate JSON datasets, schema definitions, and serialised records before ingestion into pipelines or databases.
QA Engineers
Verify that test fixture files and mock API responses are syntactically valid before running automated test suites.
DevOps & SREs
Validate Kubernetes ConfigMaps, Terraform outputs, and cloud provider API responses exported as JSON.
AI / ML Developers
Check LLM function-call outputs and JSON-mode completions for structural validity before passing them to downstream systems.
Endless Forge vs Other JSON Validators
Error context, duplicate detection, and structure analysis - all in one tool.
Validation that actually tells you what's wrong
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Frequently Asked Questions
6 questions answered