Paste both documents and select the merge strategy before running. Review the operation log and keyed-array identifiers in the resulting JSON.
Runs locally in your browser
Merge two JSON documents with explicit rules belongs to the JSON tools on KivTools. The workbench above handles the whole job on one screen: the options you pick from the form, then a text result you can copy.
The conversion runs inside the page with browser JavaScript. Nothing you enter is uploaded, the tool keeps working offline, and it is safe for data you are not allowed to send to a third party.
Structured data formats look interchangeable until one of them loses a type, a timezone or a comment. These tools read one representation, apply a documented mapping and write another, so round-tripping and column order stay predictable instead of depending on a spreadsheet export.
Most surprises come from implicit conversions: numbers turning into strings, dates shifting by a timezone, or an empty cell becoming null instead of an empty string. Convert a representative sample first and diff it against the original.
Browsers, desktop tools and command-line utilities should agree on the result; a mismatch usually means a different encoding, locale or version. Validate the converted output with a parser for the target format rather than trusting the preview alone, and keep the source file untouched until the round trip is verified.
Field order is meaningful in some formats and irrelevant in others, and quoting rules differ; when a downstream system is strict, check its own documentation rather than the general case. Keep a copy of the input while you experiment, so a wrong setting never destroys the source.
Yes. Every tool on KivTools is free, needs no account and has no usage quota. There is no paid tier hiding behind the workbench, and no email address is required to use the result.
Inside your browser. The page loads a script once and the conversion happens on your machine, which is also why the tool still works when the network drops.
The workbench takes the options you pick from the form and returns a text result you can copy. Large inputs are usually handled without trouble, but extremely large ones are better processed in a local command-line tool.
The parser is strict: either the document is valid or the reported position points at the first illegal character. Compare a small known-good sample first when the output feeds an automated pipeline.
The output is yours: no watermark, no licence tag, no attribution requirement. Check the underlying format or library licence when the result ships in a product.
The page works in any modern mobile browser, and the layout collapses to a single column on small screens. Local tools keep working offline once the page has loaded.