Formateur JSON

The formatter handles documents up to roughly 50 MB on a modern desktop browser without freezing the tab. The entire parse tree must fit in the browser's JavaScript heap before the tool can re-serialize and re-indent the output, so available RAM is the real ceiling. On Android and iOS devices, where browsers operate under tighter memory budgets, the practical limit drops to around 8–10 MB. If you paste a document above these thresholds, you may see a slow-script warning or a silent truncation of the input — both are browser-imposed, not WikiPlus limits. To work around this, split the JSON into logical chunks using your text editor, format each chunk separately, and reassemble. Alternatively, run minify first to strip all whitespace, which often cuts the payload by 30–50 % and brings an oversized document within the safe zone for subsequent formatting. A third option is to pipe large files through a local CLI tool like jq — use jq . file.json — and use WikiPlus for the interactive editing or error-hunting portion. Nothing is uploaded to a server regardless of file size. The entire parse-and-format pipeline runs in the JavaScript engine that shipped with your browser, so oversized or sensitive files never leave your machine. Once you close or refresh the tab, the content is gone from memory.

Yes — the validator applies the full RFC 8259 specification and reports the exact line and column number of the first rule violation, along with a plain-English description of the offending character or construct. Common catches include trailing commas after the last element of an array or object, which are valid in JavaScript but illegal in strict JSON; single-quoted string keys instead of the required double-quoted form; bare unquoted identifiers like undefined or NaN that are not legal JSON values; control characters embedded inside string values that must be escaped; and numbers written with a leading plus sign, which the spec disallows. The validator also detects duplicate keys within the same object level. Strictly speaking, RFC 8259 says behavior with duplicate keys is undefined, but in practice every parser that encounters them silently discards all but the last value — a silent data loss that almost always indicates an upstream bug. This tool flags duplicates as warnings even when the JSON is otherwise parseable. In lenient mode, JavaScript-style single-line comments and multi-line comments are stripped before validation, letting you quickly clean up copied code from config files or README examples. After fixing the reported error, re-run the validator — only the first error is reported per pass, so a document with cascading mistakes needs multiple correction rounds. The underlying engine is the browser's native JSON.parse, which means any document that passes here will also parse correctly in Node.js and all modern browsers.

Minify mode removes every whitespace character that is not inside a quoted string value — every space, tab, and newline used for indentation and readability — producing the most compact valid JSON representation. This matters in four concrete situations. First, HTTP API requests and responses: a minified payload transfers faster and reduces egress costs, especially on mobile networks or high-frequency polling endpoints. A typical formatted API response shrinks 30–50 % after minification. Second, URL parameters and storage keys: many systems impose strict byte limits on query strings, cookie values, JWT claims, and browser localStorage keys. Fitting structured data into a 4 KB cookie or a 2 KB URL parameter is only possible with minified JSON. Third, embedding in source code: config blobs embedded as string literals in code are far easier to manage as single-line JSON. They diff cleanly, fit on one line in log output, and are unambiguous in serialized form. Fourth, byte-level comparison: teams with different editor settings may use two spaces, four spaces, or tab indentation. Minifying both sides before a diff or hash comparison ensures indentation style is never a false positive. Minify does not alter key order, numeric precision, or Unicode escape sequences. A round trip through format-then-minify produces the same bytes as minify alone, making the operation fully deterministic and reversible. All processing runs in your browser with no server contact.

No. Every operation in the JSON Formatter — parsing, validation, formatting, and minification — runs entirely inside the JavaScript engine of the browser tab you opened. The text you paste is held only in the browser's DOM and the in-memory string passed to the native JSON.parse call. It is never serialized to a network request, never written to a server-side database, and never passed through a third-party analytics pipeline. WikiPlus does not log content, collect telemetry about what you paste, or cache the processed output between sessions. You can verify this independently in seconds: open your browser's developer tools, switch to the Network tab, clear the log, then paste a large JSON document and click Format. The network log will show zero outbound requests triggered by the formatting operation. The only network activity on the page is the initial load of static assets. This architecture is intentional. Backend engineers frequently use this tool to inspect webhook payloads from Stripe, GitHub, or Shopify. Those payloads contain customer data, API keys in headers, and internal IDs. Security-conscious teams need confidence that the content never leaves the browser. The tool was designed from day one to process data locally so that no special permissions, VPN exceptions, or data-handling agreements are needed. After you close or refresh the tab, the pasted content is released from memory entirely.