ファイルをBase64に
任意のファイルをBase64またはData URIに即座に変換
入力
クリックまたはドラッグ＆ドロップでファイルを選択
PDF、画像、音声、動画、ドキュメント（最大10MB）出力
File to Base64 Examples
Upload any file to get its Base64 or Data URI output. Example of a Data URI for a 1×1 PNG:
Sample Data URI output
Upload a file above to generate your own Base64 output.
What Is File to Base64?
File to Base64 converts any binary file into a Base64-encoded ASCII string. Unlike the Image to Base64 tool which is limited to image types, this tool accepts any file type: PDFs, audio files, video clips, Word documents, ZIP archives, fonts, and more. Base64 is defined by RFC 4648 and encodes binary data as printable ASCII text.
The output can be a full Data URI (e.g., data:application/pdf;base64,...) or just the raw Base64 string. Data URIs embed files directly in HTML, CSS, or JSON without needing separate file hosting. Processing runs entirely in your browser—no data is sent to any server. To convert Base64 back to a downloadable file, use Base64 to File.
How to Use This Tool
Upload Your File
Click the upload area, drag and drop a file, or use the Upload button. Any file type is accepted up to 10 MB. The left panel shows the file name, size, and detected MIME type.
Choose Output Format
Toggle Include data: prefix to switch between a full Data URI (ready for HTML/CSS embedding) and a raw Base64 string (for APIs or storage). The right panel updates immediately.
Copy or Download
Click Copy to put the output on your clipboard, or Download to save it as a .txt file. To decode Base64 back to the original file, use Base64 to File.
Data URI vs Raw Base64
A Data URI includes the MIME type and encoding scheme as a prefix:
Use Data URIs when embedding files in HTML, CSS, or JSON (e.g., <img src="data:image/png;base64,..."> or background-image: url(data:image/svg+xml;base64,...)). Use raw Base64 when sending to APIs that specify the MIME type separately, or when storing in a database field. The toggle on this tool lets you switch between both formats instantly.
Frequently Asked Questions
Is my data private?
Yes. Conversion runs entirely in your browser using the FileReader.readAsDataURL() API. No data is sent to any server. You can verify this by checking your browser's Network tab.
What file types are supported?
All file types are supported: images (JPG, PNG, SVG, WebP), documents (PDF, DOCX), audio (MP3, WAV), video (MP4, WebM), fonts (TTF, WOFF), archives (ZIP), and any other binary format. The MIME type is detected automatically from the file.
What is the size limit?
The tool limits uploads to 10 MB. Base64 encoding adds ~33% overhead, so a 10 MB file produces ~13.3 MB of text. Very large files may slow down the browser. For huge files, consider command-line tools like GNU base64.
Can I embed a PDF in HTML?
Yes. Upload your PDF, enable the Data URI toggle, and use the output as: <embed src="data:application/pdf;base64,..." type="application/pdf">. Browser support for embedded PDFs varies. For large PDFs, an external URL is usually better for performance.
How do I convert Base64 back to a file?
Use the Base64 to File tool. Paste your Base64 string, specify the filename and MIME type, and download the reconstructed file.
Related Tools
For the Base64 specification, see RFC 4648. MDN's Data URIs guide covers embedding. FileReader API handles file reading in the browser.