Precision-engineered json formatter, validator & fixer for the modern web.
About JSON Formatter, Validator & Fixer
JSON Formatter, Validator & Fixer gives you a reliable, private way to encode, decode, validate and reformat structured data directly in your browser. The tool recognises and handles common serialisation formats with lossless round-tripping, surfaces parse errors with precise line and column hints, and supports bulk operations on multi-megabyte inputs. Everything is processed on-device — so PII, secrets and production payloads never leave your machine.
Problems This Tool Solves
Online encoders and decoders routinely log every payload for "analytics", which is a compliance non-starter for sensitive data. - JSON Formatter, Validator & Fixer processes everything locally — no payload is logged, stored or transmitted.
Hand-editing structured data is a fast way to break quoting, escaping or indentation. - JSON Formatter, Validator & Fixer parses, validates and re-emits clean output that is guaranteed to round-trip.
Parse errors in JSON, YAML or XML often point to misleading line numbers. - JSON Formatter, Validator & Fixer surfaces the true cause with precise line, column and token context.
Large payloads crash browser-based tools that load everything into memory at once. - JSON Formatter, Validator & Fixer streams input through a WebAssembly parser that scales cleanly into the multi-megabyte range.
How to Use
Paste or drop your input - Supports text paste, file drag-and-drop and URL loading from your clipboard.
Auto-detect format - The parser inspects the first bytes to detect the input format automatically.
Validate and transform - Syntax is checked against the live spec, errors are highlighted inline and output is pretty-printed.
Copy or export - Copy to clipboard, download as a file or push to the companion tool for the next step.
Why This Tool Is Better
Handles production-sized input - The engine is stream-based, so 50 MB JSON dumps and multi-line base64 blobs parse cleanly without freezing the browser.
Precise error reporting - Every parse error includes line, column, token and a human explanation — not just "unexpected token".
Round-trip safe - Decode-then-encode always reproduces the original bytes, which matters when the payload is a signature or a cryptographic token.