JSON Viewer &
Formatter
Paste JSON to format, validate, and explore with syntax highlighting. Prettify or minify instantly in your browser.
Formatted output will appear here...
How It Works
Paste JSON
Paste any JSON string into the input area.
Format & Explore
Instantly see formatted, syntax-highlighted output.
Copy or Minify
Copy the prettified or minified version to clipboard.
Format and validate JSON online with syntax highlighting, expandable trees, and instant error reporting. ConverterUp's JSON viewer is built for backend developers, API consumers, and data analysts who need to inspect responses, beautify minified payloads, or quickly minify JSON before pasting it into a config file. Drop a file or paste the text, expand and collapse nested objects, and copy the prettified or compact result. The JSON is parsed locally in your browser, so private API responses, tokens, and customer data never reach a remote server.
When to use a JSON viewer
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 a navigable tree, surfaces 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.
ToolSeo.json-viewer.section1.p4
ToolSeo.json-viewer.section1.p5
Features: format, validate, minify, tree view
Pretty-print indents and aligns the document with a configurable tab or space width, 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.
Tree view renders objects and arrays as expandable nodes with key counts, so you can drill into a deeply nested payload without scrolling through thousands of lines. Syntax highlighting colors strings, numbers, booleans, and null distinctly to spot type mistakes at a glance.
Validation happens live as you type. Errors point to the exact line and column with a short message — unexpected token, trailing comma, unterminated string, duplicate key. The viewer enforces strict RFC 8259 JSON, so JSON5 quirks (comments, single quotes, hex numbers, trailing commas) are surfaced as errors rather than silently accepted.
ToolSeo.json-viewer.section2.p4
ToolSeo.json-viewer.section2.p5
Common JSON errors and how to fix them
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 viewer highlights the line where the parser gave up; from there, walk backward to find the unmatched pair.
ToolSeo.json-viewer.section3.p5
ToolSeo.json-viewer.section4.heading
ToolSeo.json-viewer.section4.p1
ToolSeo.json-viewer.section4.p2
ToolSeo.json-viewer.section4.p3
ToolSeo.json-viewer.section4.p4
ToolSeo.json-viewer.section4.p5
ToolSeo.json-viewer.section5.heading
ToolSeo.json-viewer.section5.p1
ToolSeo.json-viewer.section5.p2
ToolSeo.json-viewer.section5.p3
ToolSeo.json-viewer.section5.p4
ToolSeo.json-viewer.section5.p5
Frequently asked questions
How are JSON errors reported?
Invalid JSON is highlighted at the exact line and column where the parser failed, with a short description such as unexpected token or trailing comma. Fix the issue and the tree view updates automatically.
What is the maximum JSON size?
Files up to 25 MB parse smoothly on most laptops. Above that, the tree view may become slow because the browser has to render thousands of nodes. Use minify mode for very large payloads.
What is the difference between minify and beautify?
Beautify (or pretty-print) adds indentation and line breaks so JSON is human-readable. Minify removes every byte of whitespace to produce the smallest valid payload — useful for HTTP bodies, environment variables, or copying JSON into a single-line string.
Does it support JSON5, JSONC, or comments?
No. The viewer enforces strict JSON per RFC 8259, so trailing commas, single quotes, hex numbers, and comments are flagged as errors. Strip JSON5 / JSONC extensions in your source first, or use a JSON5-to-JSON converter before pasting.
Can I sort or search inside the JSON?
Yes. The tree view supports a key/value search box that filters nodes as you type and shows the path of each match. Sorting keys alphabetically is available with a single toggle.
Is my JSON sent to a server?
No. Parsing, formatting, validation, and minification all run client-side. ConverterUp has no logging endpoint for JSON content, which is critical when debugging payloads with credentials, tokens, or PII.
ToolSeo.json-viewer.q7
ToolSeo.json-viewer.a7
ToolSeo.json-viewer.q8
ToolSeo.json-viewer.a8