# JSON File Merger Merge multiple JSON files with various merging strategies (deep merge, overwrite, combine arrays, etc.) > Canonical page: https://elysiatools.com/en/tools/json-merger - **Category:** Data Processing - **Keywords:** json, merge, combine, objects, data, files ## Overview The JSON File Merger is a powerful utility designed to combine multiple JSON files into a single, unified document using customizable merging strategies, including deep recursive merging, array concatenation, and conflict resolution. ## Inputs - **JSON Files** (file): Select JSON files to merge... - **Merge Strategy** (select) - **Array Handling** (select) - **Conflict Resolution** (select) - **Output Format** (select) ## When to use - Consolidating configuration files from different environments into a single master file. - Merging fragmented data exports from multiple API endpoints or database queries. - Aggregating localized language files or translation sets into one comprehensive JSON structure. ## How it works - Upload your JSON files using the file selector. - Select a merge strategy, such as 'Deep Merge' for nested objects or 'Overwrite' for simple replacement. - Configure how arrays should be handled, choosing between concatenation, unique merging, or replacement. - Set your conflict resolution preference and download the final, formatted JSON output. ## Use cases - Merging environment-specific configuration files (e.g., dev.json, prod.json) into a single deployment config. - Combining multiple JSON-based log files into a single chronological data set. - Aggregating user-generated data exports from different sessions into one master record. ## Frequently asked questions ### What is the difference between deep and shallow merge? A deep merge recursively combines nested objects, while a shallow merge only combines top-level properties, with later files overwriting earlier ones. ### Can I merge arrays instead of replacing them? Yes, you can select 'Concatenate' or 'Merge Unique' in the Array Handling settings to combine array contents rather than overwriting them. ### What happens if two files have the same key? You can define the behavior in the Conflict Resolution settings, choosing to overwrite with the last value, keep the first value, or stop the process with an error. ### Is there a limit to the number of files I can merge? You can upload up to 5 files at a time, with a total file size limit of 10MB. ### Can I format the output file? Yes, the Output Format option allows you to choose between standard, compact, or prettified JSON with 4-space indentation. ## Related tools - [TXT File Merger](https://elysiatools.com/en/tools/txt-merger): Merge multiple text files with various strategies (concatenate, interleave, etc.) - [Time Series Anomaly Detector](https://elysiatools.com/en/tools/time-series-anomaly-detector): Upload CSV or JSON time series data, detect anomalies with Z-Score and IQR methods, and return a chart-backed report - [Dataset Imbalance Detector & Resampler](https://elysiatools.com/en/tools/dataset-imbalance-detector-resampler): Detect class imbalance in CSV or JSON datasets, compare resampling strategies, and preview a balanced output dataset - [Mock Data Prefix / Abbreviation Conflict Detector](https://elysiatools.com/en/tools/mock-data-naming-conflict-detector): Detect visually confusing field names and prefix collisions in CSV, JSON, or schema inputs, then suggest clearer renames - [Fitness Workout PDF Generator](https://elysiatools.com/en/tools/fitness-workout-pdf-generator): Generate a printable workout-plan PDF from JSON or CSV data with exercise tables, progress boxes, and optional QR video links - [2026 PDF Calendar Designer](https://elysiatools.com/en/tools/pdf-2026-calendar-designer): Design and export stylish 2026 printable PDF calendars with bimonthly, quarterly, semiannual, or annual single-page layouts - [Markdown Merger](https://elysiatools.com/en/tools/markdown-merger): Merge multiple markdown files with smart header level adjustment and table of contents generation - [YAML File Merger](https://elysiatools.com/en/tools/yaml-merger): Merge multiple YAML files with various strategies (deep merge, overwrite, combine arrays, etc.) ## Samples - [Chat Transcript JSON Samples](https://elysiatools.com/en/samples/chat-transcript-json): JSON examples for multi-role chat transcripts - [Rich Media JSON Samples](https://elysiatools.com/en/samples/rich-media-json): JSON examples for popular rich text editors (TipTap, Quill, Slate) - [JWT Samples](https://elysiatools.com/en/samples/jwt-samples): Comprehensive JWT examples from basic token structure to advanced security implementations - [Terraform Plan JSON Samples](https://elysiatools.com/en/samples/terraform-plan-json-samples): Sample Terraform plan JSON files exported from terraform show -json style payloads for dependency visualization and change review ## Related content - [JSON Inspection, Diff, and Transformation Tools](https://elysiatools.com/en/hubs/json-utility): Compare JSON formatting, diffing, path inspection, schema validation, merging, transformation, and export tools in one hub for API and data workflows. - [JSON Interchange and Format Translation Tools](https://elysiatools.com/en/hubs/json-convert): Compare JSON conversion tools for CSV, YAML, TOML, GraphQL, XML, Markdown, Excel, BSON, EDN, and related structured formats in one hub. - [Text Case, Encoding, and Normalization Conversion Tools](https://elysiatools.com/en/hubs/text-convert): Compare text case conversion, character-width conversion, encoding conversion, quoted-printable handling, and inline text normalization tools in one hub. - [Text Tools](https://elysiatools.com/en/hubs/text-utility): Explore 33 text tools for utility workflows and compare closely related utilities quickly.