Bulk Base64 Converter
Convert multiple files to Base64 at once. Upload several images, documents, or files and get Base64-encoded output for all of them simultaneously.
Select multiple files (images, documents, etc.) to convert to Base64
Files ()
What Is Bulk Base64 Conversion?
Bulk Base64 conversion is the process of encoding multiple files into Base64 strings in a single batch operation. Instead of converting one file at a time, the bulk converter reads each file through the browser's FileReader API and outputs a Base64 string for every file in the queue. The result is a collection of encoded strings you can copy individually or export as a single JSON file. This tool processes everything client-side, so no data leaves your device. If you need to encode individual files to Base64, a dedicated single-file tool is also available.
What Are the Common Use Cases for Bulk Base64 Conversion?
Bulk Base64 conversion serves four primary scenarios. Each involves converting multiple files at once rather than processing them one by one.
Batch Image Processing: Convert product images, thumbnails, or icon sets to Base64 for inline embedding in HTML or CSS. A set of 20 icons can be converted in one operation and used directly in stylesheets without additional HTTP requests. You can also encode single images to Base64 when only one file is needed.
API Payload Preparation: REST and GraphQL APIs that accept Base64-encoded file uploads require each file as a string. Bulk conversion generates all strings at once, ready for inclusion in JSON request bodies.
Documentation Embedding: Technical documentation tools that support inline images accept Base64 data URIs. Convert an entire folder of screenshots or diagrams in one batch to embed them without external image hosting.
Data Migration and Backup: When moving files between systems, Base64 provides a text-safe transport format. Bulk conversion creates a JSON export that preserves file names and encoded content together.
How Does the Bulk Base64 Converter Work?
The converter follows three steps. Each file is processed independently using the browser's native FileReader and btoa() functions. No server-side processing is involved.
Step 1 -- Select Multiple Files: Click the file input and select multiple files using Ctrl+Click (Windows/Linux) or Cmd+Click (macOS). The tool accepts any file type: images, PDFs, text files, and binary files.
Step 2 -- Click Convert: Press the "Convert All to Base64" button. The converter reads each file sequentially into an ArrayBuffer, converts the bytes to a binary string, and encodes it with btoa(). A status indicator shows progress for each file.
Step 3 -- Download Results: Copy any individual Base64 string to the clipboard, download a single file as a .txt, or click "Download All as JSON" to export every file's name and Base64 data in one .json file.
What Output Formats Are Available?
The bulk converter provides three output options. Each format suits a different integration workflow. You can also use the embed code generator to produce ready-to-use HTML or CSS snippets from Base64 strings.
| Output Option | Format | Use Case |
|---|---|---|
| Individual Strings | Raw Base64 per file | Copy-paste into code |
| JSON Export | {"filename": "base64..."} |
API payloads, config files |
| Data URIs | data:[MIME];base64,... |
HTML/CSS embedding |
What Are the Performance Considerations for Bulk Conversion?
Performance depends on file count, individual file size, and device memory. The converter processes files sequentially in the browser's main thread. Keep these numbers in mind for smooth operation.
File Size: Individual files under 5 MB convert in under 1 second on most devices. Files between 5 MB and 50 MB may take several seconds each. Base64 encoding increases output size by approximately 33%, so a 3 MB image produces a roughly 4 MB string.
Batch Size: Batches of 50-100 files process without issues on modern browsers. Batches above 200 files may cause tab slowdowns on devices with less than 8 GB of RAM. Splitting large sets into smaller batches is recommended.
Browser Limits: The FileReader API handles files up to approximately 500 MB, but practical limits are lower due to memory constraints. Total batch memory consumption equals roughly 2.66x the combined original file sizes (raw bytes plus Base64 output).
Is Bulk Base64 Conversion Private and Secure?
Yes. Every file is read and encoded entirely within your browser. No data is transmitted to any server. The tool uses the native FileReader API to read files from your local filesystem and btoa() to perform the encoding. Network activity is zero during conversion. After you close or refresh the page, all file data and Base64 output are cleared from browser memory. This makes the tool suitable for confidential documents, internal assets, and personally identifiable information. To verify output integrity, you can validate Base64 output with a dedicated checker. For more Base64 tools, see the full collection on the homepage.
Frequently Asked Questions
How many files can I convert at once?
There is no hard-coded file count limit. The practical limit depends on your browser's available memory. Most modern browsers handle 50-100 files per batch without issues. Batches above 200 files may cause tab slowdowns on devices with less than 8 GB of RAM. For very large sets, split files into batches of 50 and process them sequentially.
What is the maximum file size for bulk conversion?
Each file can be up to the browser's FileReader limit, which is typically around 500 MB. For best performance, keep individual files under 5 MB and total batch size under 100 MB. Base64 encoding increases output size by approximately 33%, so plan memory usage accordingly.
Does bulk conversion maintain the original file names?
Yes. The converter preserves each original file name in the output. When you download results as JSON, each entry includes the filename property mapped to its Base64 string. Individual .txt downloads also retain the source file name with a .base64.txt extension appended.
Can I convert mixed file types in one batch?
Yes. The bulk converter accepts any file type in a single batch. You can mix images (PNG, JPEG, WebP), documents (PDF, DOCX), text files, and binary files. Each file is independently read and encoded to Base64 regardless of its MIME type. The JSON export includes all files together.