A logged API response or a hand-edited fixture arrives as one unbroken line, and you cannot see the nesting you need to debug.
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JSON Formatter
JSON
Free · API · MCPToolYour platform
Use JSON Formatter three ways
The free JSON Formatter on this page works in your browser. The same workflow is available via REST API for apps and via MCP for Cursor, Claude, and other agents — one API key, one plan, one quota. This tool is part of the developer-apis module under Developer Tools.
- Free in browserUse JSON Formatter here — no account required.
- REST APICall from your server with
X-Api-Key. - MCP for agentsConnect Cursor or Claude to ToolYour MCP with the same key.
- 1. Get an API keySign in and open Dashboard → API Keys (works for REST and MCP).
- 2. Call or connectUse the REST API from your server, or paste the MCP URL into your agent config.
- 3. Same qualityOutput matches the free web tool across all three surfaces.
What is JSON Formatter?
A logged API response or a hand-edited fixture arrives as one unbroken line, and you cannot see the nesting you need to debug. This JSON formatter parses the document first, then re-serialises it with the indentation you choose — two spaces by default, or zero when you ask it to minify for the wire.
Parsing happens before formatting, which is the important part: a document with a trailing comma or an unquoted key fails with the parser's own error message rather than being quietly "fixed" into something that no longer matches what your service sent. Input is capped at 512,000 characters per call. If you only need a pass or fail answer and the root type, JSON Validator is the lighter call.
Browser use is free and needs no signup. The same job runs over REST at POST https://api.toolyour.com/api/v1/developer-apis/json-formatter and over MCP at https://api.toolyour.com/mcp — one API key, one shared monthly credit pool, 1 credit per successful call.
What are common questions about JSON Formatter?
Can it minify as well as pretty-print?
Yes. Send minify: true or space: 0 and the parsed document is re-serialised with no whitespace at all.
What happens when the JSON is invalid?
You get the parse error and no output. Nothing is rewritten or guessed, so a broken payload stays visibly broken.
Does it preserve key order?
Yes. Keys are re-serialised in the order the parser saw them; the formatter never sorts or renames fields.
How large a document can I send?
Up to 512,000 characters per call. Split larger dumps locally, or stream them through your own tooling first.
What are the key features of JSON Formatter?
Indent or minify in one call
Choose an indent width for reading, or collapse to a single line for transport.
Strict parse before output
Malformed JSON fails loudly with the parser message instead of producing a plausible-looking fake.
Same transform on REST and MCP
Scripts and agents call the identical route, so formatted fixtures match what you saw in the browser.
How do you use JSON Formatter?
Paste the JSON
A response body, a config file, or a fixture you are about to commit.
Pick indent or minify
Two spaces is the default; set minify when you care about bytes on the wire.
Copy the result
Drop it into a diff, a document, or the next step of an agent pipeline.
When formatting is the fastest debugging step
Three situations come up constantly. Reading a logged payload — webhook and gateway logs store bodies as single-line strings, and nesting only becomes obvious once it is indented. Reviewing a fixture diff — a minified fixture produces a one-line diff that hides which field actually changed, while a formatted one produces a reviewable diff. Shrinking a config — the reverse job, where an indented document goes out minified to save bytes in an environment variable or a query string.
In all three cases the parse step is doing quiet work. If the payload does not parse, formatting was never the real problem, and you have found the bug earlier than you would have by eye.
How this fits the JSON cluster
Formatting is usually the first stop. From here, JSON Validator answers pass or fail and reports the root type, JSON to TypeScript turns the same sample into a starting type, and JSON to YAML converts it for a config repository that prefers YAML.
For agents, the ordering matters: validate before you format, and format before you hand a payload to a codegen step, so a parse failure surfaces in the cheapest call rather than three steps later.
Which core developer tools sit in this cluster?
Where do you browse more developer tools tools?
- Developer Tools tools
Browse the full Developer Tools category on ToolYour.
- Marketing Tools tools
Build UTM links, check ads copy limits, QA email subjects, and calculate ROAS/CPC/CTR — free in the browser; R
- Security Tools tools
Check HTTP security headers, TLS, cookies, JWTs, passwords, hashes, and SPF/DKIM/DMARC — free in the browser;
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