JSON Viewer &
Formatter

JSON is everywhere — REST APIs, NoSQL stores, config files, build outputs, log lines — but raw JSON is rarely human-readable. A dedicated viewer turns a flat blob into an indented, color-highlighted document, flags syntax errors as you type, and lets you switch between a pretty-printed view (for reading) and a minified view (for pasting into env vars or strings).

Typical tasks include inspecting an API response while building a frontend, comparing two payloads diff-style, hunting down a missing comma or extra bracket in a config file, validating that a webhook body matches a schema, and beautifying a one-line JSON dump pulled from a log aggregator.

ConverterUp's viewer runs entirely in your browser. Nothing is uploaded, nothing is logged. That matters when the JSON contains API keys, customer PII, or unreleased response shapes — exactly the cases where pasting into a random web tool would be reckless.

Prettify indents the document with two spaces, useful for sharing in PRs or pasting into documentation. Minify strips all whitespace to produce the smallest possible payload, which is what you want for HTTP bodies, query strings, or copying into JSON-as-string fields.

Syntax highlighting colors keys, strings, numbers, booleans, and null distinctly so you can spot type mistakes at a glance. Expand the preview to read long payloads comfortably, or collapse it to keep the page compact.

Validation happens live as you type: a Valid / Invalid JSON badge shows the state, with the parser's error message when something is wrong. The viewer uses strict JSON parsing, so JSON5 quirks (comments, single quotes, hex numbers, trailing commas) are reported as errors rather than silently accepted.

Trailing commas — {"a":1,} is invalid JSON. Most languages and editors permit them, JSON does not. Remove the comma after the last item in any object or array.

Single quotes — {'a':1} looks fine in JavaScript but is not JSON. Keys and string values must use double quotes. Run a find-and-replace from ' to " if your source comes from a JavaScript dump.

Unescaped characters in strings — newlines, tabs, and backslashes inside string values must be escaped as \n, \t, and \\. Pasting a raw multi-line string is a frequent cause of unexpected token errors.

Missing brackets — large hand-edited files often end up with an unbalanced bracket or brace. The error message tells you where the parser gave up; from there, walk backward to find the unmatched pair.