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JSON File Merger

Merge JSON files into one array, one object, or keyed by filename.

  • Free
  • No signup
  • Nothing uploaded
  • No watermark

Drop files here

JSON files — add as many as you need · read on your device, never uploaded

How to Use the JSON File Merger Online

JSON File Merger: before and after JSON A BEFORE JSON FILEMERGER JSON A AFTER

Drop in two or more .json files and get one file back. You choose the shape: one array of everything, one merged object where later files win on shared keys, or an object keyed by filename. The keyed option keeps each file under its own name, so nothing overwrites anything and you can still tell where a record came from.

Merges JSON files into one array, one object, or keyed by filename. Keyed by filename is the option worth knowing about — it preserves which record came from which source, which a flat merge discards.

No software to install Free Works on any device

Step-by-Step Guide to Using the JSON File Merger

  1. 1. Drop your files in, or click to choose them

    Two or more.

  2. 2. Drag them into the order you want, and set how they should be joined

  3. 3. Press Merge, then download the single file that comes out

No .json file to hand? Download a sample JSON file (3.5 KB) and try it.

Try it now

What is the JSON File Merger?

Merges JSON files into one array, one object, or keyed by filename. Keyed by filename is the option worth knowing about — it preserves which record came from which source, which a flat merge discards.

JSON file

.JSON

Merge JSON files into one array, one object, or keyed by filename.

At a glance

  • Takes: .json files, as many as you need
  • Gives: One .json file in the shape you picked
  • Shapes: One array, one merged object, or an object keyed by filename
  • Handles: Arrays are flattened one level; a file holding a single object is added as one item
  • Runs: Read and written in your browser tab, so the files stay on your machine
  • Price: Free, no signup, no file cap set by a server

Why Inspect a Document Before Sending?

A file can look fine on screen and still fail a portal check because of its version, page size, fonts or hidden permissions. Inspecting it first shows those details plainly, and the helper tools split, merge and shrink data and office files.

“Check the file before someone else rejects it.”
  • Page count and size at a glance
  • Version and standard checks
  • Hidden attachments brought out
  • Data files split or merged
  • Fonts and links listed
  • Permissions shown before you share
  • Office files made smaller
  • Excel formulas explained

Popular Uses for Document Checkers

These checks answer the questions people have about a file before it goes anywhere.

  • Print shop checks Confirm page sizes, orientation and PDF/X before sending artwork to a printer.
  • Archive submissions Check whether a PDF meets PDF/A before submitting it to a court or registry.
  • Counting pages and words Find the page count and word count of a PDF for a quote or limit.
  • Checking links List every link inside a PDF to find broken or outdated addresses.
  • Font problems See which fonts a PDF uses and whether they are embedded for printing.
  • Shrinking Office files Make a heavy Word, Excel or PowerPoint file smaller before emailing it.
  • Splitting large CSVs Cut a huge CSV or JSON file into parts that other tools can open.
  • Excel formula help Check a formula for errors or turn a column number into its letter.

What You Can Do with the JSON File Merger

Understands JSON structure rather than treating the file as bytes

Splits on record boundaries rather than byte counts, so no row or object is cut in half

Preserves the original encoding and line endings instead of normalising them silently

Why Use ToolXkit for JSON File Merger?

Your files stay with you

Everything runs inside your browser. Nothing you open or type is uploaded to a server.

Document Inspection for Different Users

Printers and publishers

Check PDF/X, page sizes and fonts before a job goes to press.

Legal professionals

Confirm PDF/A compliance, page counts and permissions before filing documents on a court portal.

Translators

Count words in a PDF to quote a fair price for a translation.

Data analysts

Split, merge and count rows in CSV and JSON files too big to open.

Office administrators

Check file sizes, versions and security settings before uploading to portals.

Web teams

Extract links and bookmarks from PDFs before publishing them on a website.

Best Times to Check a PDF or Data File

Inspection tools are worth a look when you are:

  • Sending artwork to a printer
  • Filing papers on a court portal
  • Quoting a translation job
  • Opening a CSV too big for Excel
  • Checking why a PDF was rejected
  • Sharing a file with restrictions
  • Emailing a heavy PowerPoint deck
  • Auditing links in a brochure

Tips and Good to Know

  1. Merging into one object needs every file to hold an object at the top level. If one holds an array, pick one array or keyed by filename instead.

  2. It does not merge records by an ID field. Two files with the same customer in each give you that customer twice in an array.

  3. For CSV exports use CSV File Merger, which matches columns by header name; JSON has no headers to match.

Frequently Asked Questions

Answers to common questions about this tool.

Do I need to install anything to use the JSON File Merger?

No. JSON File Merger runs entirely in your browser — there is nothing to download, no extension and no desktop program. It works the same on Windows, macOS, Linux, Android and iPhone.

Is it safe to use the JSON File Merger online?

Safer than the usual alternative, yes. Most online tools upload your file to a server you know nothing about, where it sits until someone deletes it. Here the file never leaves your device — the processing happens in the page itself, so there is no server copy to leak, retain or sell.

Does JSON File Merger change my file?

The inspection tools only read the file and report what they find, so your document is untouched. Tools that split, merge or compress give you a new file and leave the original as it was.

What is PDF/A and do I need it?

PDF/A is a version of PDF made for keeping documents readable for many years. Some courts, government offices and archives ask for it. If a portal does not mention it, an ordinary PDF is fine.

Can I use JSON File Merger without signing up?

Yes. No account, no email and no fee. Drop in the file and the report or result appears on the page, ready to read or download.

Why was my PDF rejected by a portal?

Common reasons are a file that is too large, the wrong PDF version, a password, missing fonts or pages of the wrong size. Checking those details here usually points to the cause.

Further reading

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