How can I merge multiple JSON arrays?

Upload multiple JSON files containing arrays, select 'Concatenate Arrays' mode, and the tool will combine all arrays into a single array. You can also wrap multiple files in a parent array.

How can I split a large JSON file?

Switch to Split mode, upload your JSON file, then choose to split by item count (e.g., 100 items per file) or by top-level keys. The tool will generate multiple smaller JSON files.

What are common use cases for JSON merge and split?

Common use cases include data migrations, batch processing large datasets, combining API responses, splitting files for parallel processing, and preparing test data fixtures.

JSON Merger & Splitter

Merge multiple JSON files into one, or split large JSON by item count or top-level keys. Great for migrations, batch jobs, and test data prep. Processing stays in your browser.

call_merge Merge JSON Files

Upload multiple files or paste JSON snippets (one per line). Owly will merge them in order.

upload_file Upload files

Inputs

Merge strategy Deep merge objects

Merged Output

Output is pretty-printed JSON. For extremely large files, splitting may be faster.

call_split Split JSON

Split a large JSON into smaller files by array chunk size or by top-level keys.

upload_file Upload

Input JSON

Split mode Items per file

Tip: splitting by size (bytes) can be added if you want strict file-size targets.

Split Output

Paste JSON and click Split.

Notes

Merge order matters: later files overwrite earlier keys when merging objects.
Array splitting uses item counts (e.g. 100 items per file).
Key splitting creates one file per top-level key (for objects).