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Combine multiple JSON documents or arrays into a single consolidated file

Combine multiple JSON documents or arrays into a single consolidated JSON file.

🛡️ Your rows never leave your browser.

Why Onfyt: Supports both array concatenation and deep recursive object merging in a single client-side tool.

Interactive Sample Data

id	source_file	name	email
101	part1.json	Grace Kerubo	grace@corp.com
102	part1.json	Peter Njoroge	peter@corp.com
201	part2.json	Mercy Akinyi	mercy@corp.com

How this tool works

When exporting paginated API endpoints, microservice event logs, or chunked document database backups, records frequently arrive split across dozens of separate files—such as 'users_page_1.json', 'users_page_2.json', through 'users_page_50.json'. Combining these files manually by opening each document and carefully copying bracketed blocks between commas is tedious and prone to syntax errors (such as leaving trailing commas or orphaned closing brackets). Alternatively, when merging configuration files, you need a deep recursive merge where properties from File B override File A without wiping out nested sub-objects. DataFix supports both array concatenation and deep object merging. Drag and drop all your JSON files simultaneously. For array datasets, DataFix concatenates all elements into a single unified array with optional deduplication on primary keys. For configuration objects, it performs deep recursive property merging, producing clean, formatted, valid JSON ready for immediate use. Combining multiple JSON files into a consolidated document or array merges distributed log outputs and configuration sets with automatic schema conflict resolution. Consolidating distributed JSON files into unified collections merges fragmented records with automated schema reconciliation and array concatenation.

Things that usually go wrong

Append mode includes duplicate objects if they exist in multiple files.
Join mode requires a common key field in all files — missing keys produce incomplete merged objects.

Edge cases we tested

🧪 Files containing single objects mixed with files containing arrays

Wrapped into a unified array structure without syntax errors.

🧪 Duplicate records existing across files

Optional deduplication toggle drops duplicate IDs during concatenation.

🧪 Deeply nested conflicting keys in object merge mode

Sub-objects merged recursively; scalar values resolved via chosen priority rule.

Frequently Asked Questions

How many files can I merge?

Up to 10 files.

Can I merge arrays from different APIs?

Yes — as long as each file contains a JSON array at the root.

Can I merge a JSON file with a CSV file?

Not directly. Convert the CSV to JSON first using the CSV to JSON tool, then merge the resulting JSON arrays.

What if one file has extra keys that the other doesn't have?

In append mode, all keys from all files are included in the merged array. Objects missing a key have that key set to null in the output.

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