Folder Compare Online
Compare two folders by uploading files. Find added, removed, and modified files.
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About Folder Compare Online
Compare two folders and find added, removed, and modified files. Upload two directories to compare their contents including file names and sizes. Free online tool — no signup, 100% private. All processing happens in your browser — nothing is uploaded to any server.
What Is Directory Comparison?
Directory comparison (also called folder diff or folder sync analysis) is the process of examining two folder structures to identify differences. This includes finding files that exist only in one folder, files that exist in both but have different sizes or content, and files that are identical across both directories. Directory comparison is a fundamental operation for backup verification, deployment validation, and synchronization workflows.
How Does Nested Folder Comparison Work?
Our folder compare tool fully supports nested directory structures. When you upload a folder, the browser reads all files recursively, preserving the complete relative path including all subdirectories. The comparison uses these relative paths as keys — so a file at src/utils/helper.js in Folder 1 is compared against the same path in Folder 2. This means you can compare deeply nested project structures, node_modules directories, or multi-level asset folders and see exactly which files at which paths have changed.
Understanding the Comparison Results
The folder comparison produces three categories of results. "Only in Folder 1" shows files that were removed or don't exist in the second folder — these are highlighted in red. "Only in Folder 2" shows new files that were added — highlighted in green. "In Both Folders" shows files present in both directories, with modified files (different sizes) highlighted in yellow. The summary statistics at the top give you an immediate overview of how many files fall into each category.
Folder Synchronization Use Cases
Folder comparison is the first step in any synchronization workflow. Before syncing, you need to know what has changed. Our tool helps you identify which files need to be copied, updated, or deleted to bring two folders into alignment. Common use cases include comparing a local project folder against a backup, verifying that a deployment folder matches the build output, comparing two versions of a website's asset directory, or auditing changes between two snapshots of a shared drive.
Comparing Project Directories
Developers frequently need to compare project directories — perhaps comparing a feature branch checkout against the main branch, or verifying that a build process produced the expected output files. Our tool makes this easy by showing all file-level differences at a glance. Combined with our other comparison tools (text compare, code compare, binary compare), you can drill down into specific files that differ to see exactly what changed.
Privacy and Browser-Based Processing
All folder comparison happens entirely in your browser. When you select a folder, the browser's File System API reads the directory structure and file metadata locally. No files or folder contents are ever uploaded to any server. This makes it safe to compare sensitive project directories, proprietary codebases, or confidential document folders without any privacy concerns. The tool works completely offline once the page is loaded.
Frequently Asked Questions
Can I compare folders with nested subdirectories?
Yes, the folder compare tool fully supports nested directory structures of any depth. When you upload a folder, all files in all subdirectories are included in the comparison. The tool preserves the complete relative path (e.g., src/components/Button.js) and uses it to match files between the two folders. This means deeply nested structures are compared accurately with their full paths shown in the results.
How does the tool determine if files are modified?
The tool compares files by their relative path and file size. If a file exists at the same path in both folders but has a different file size, it is flagged as modified (shown in yellow). While size comparison catches most modifications, identical-size files with different content would not be flagged. For content-level comparison of specific files, use our binary compare or text compare tools after identifying potentially modified files.
Can I use this tool to sync two folders?
This tool is designed for comparison and analysis rather than synchronization. It shows you exactly what differs between two folders — which files are added, removed, or modified — giving you the information needed to perform a manual or automated sync. You can use the results to identify which files need to be copied, updated, or deleted to synchronize the directories.
Is there a limit on the number of files I can compare?
There is no hard-coded file limit. The tool runs in your browser, so performance depends on your device's memory and processing power. It handles folders with thousands of files efficiently. For extremely large directories (tens of thousands of files), comparison may take a few seconds but will still complete successfully. The browser's directory upload API handles the file reading automatically.
Are my folder contents uploaded to any server?
No. All processing happens 100% locally in your browser. The folder contents are read using the browser's webkitdirectory API and compared entirely on your device. No file data, file names, or folder structures are ever sent over the network. You can verify this by monitoring network activity in your browser's developer tools — no requests are made during comparison.