Base64 File Converter — Encode & Decode Files Online Free
Free online Base64 file converter. Convert any file to Base64 string or decode Base64 back to its original file format — images, PDFs, and more.
To convert a file to Base64, drop it in the File to Base64 area and copy the result; to turn Base64 back into a file, paste it under Base64 to File and click Download File.
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Base64 File Converter — Encode & Decode Files Online Free. Free online Base64 file converter. Convert any file to Base64 string or decode Base64 back to its original file format — images, PDFs, and more.
Use our free Base64 file converter to encode any file — images, PDFs, documents — into a Base64 string, or decode a Base64 to file instantly in your browser. Our file to Base64 converter runs entirely client-side, so your files never leave your device.
Ideal for embedding images in CSS or HTML, encoding binary payloads for APIs, or debugging data URIs. No upload, no signup required. Developers use Base64 encoding to transmit binary data safely over text-based protocols.
Our tool makes it easy: upload any file to get its Base64 string instantly, or paste a Base64 string and download the decoded file. Supports all file types including PNG, JPEG, PDF, and executables. Related: Base64 String Converter, Base64 Image Decoder.
Frequently asked questions
How do I convert a file to a Base64 string?
In the File to Base64 card, drag a file onto the upload area or click to select one. The encoded text appears below as a data URI, starting with data: followed by the MIME type and ;base64, and Copy Base64 puts it on your clipboard. Delete everything up to and including the comma if you only need the raw Base64.
How do I decode Base64 back to a file?
Paste the string into the Base64 to File box, set the File Name and Extension, and click Download File. The file type is read from a data URI prefix if there is one, otherwise from the first decoded bytes, so PNG, JPEG, GIF, WebP, SVG, BMP, ICO, TIFF, AVIF, PDF, ZIP and a few more fill in the Extension field automatically.
Does Preview Image need a data URI prefix?
No. Raw Base64 works too: the tool decodes the first bytes, recognises PNG, JPEG, GIF, WebP, SVG, BMP, ICO, TIFF and AVIF images by their signature and builds the data URI for you. Non-image data such as a PDF shows a note with the detected type instead of a preview; use Download File for those.
Why does it say Invalid Base64 string?
The text contains characters that are not valid standard Base64 or its padding is wrong. Standard Base64 uses A to Z, a to z, 0 to 9, + and / with = padding at the end; spaces and line breaks are ignored. URL-safe Base64 that uses - and _, or strings with the padding removed, are rejected.
Are my files uploaded to a server?
No. Files are read with the browser's FileReader and decoding happens locally, so nothing is sent to a server. Very large files produce very long strings, which can make the page slow.
How to use this online tool
Base64 File Converter — Encode & Decode Files Online Free is designed for fast browser workflows when you need to format, validate, convert, decode, encode, generate, or inspect data without opening a heavy desktop app. Start with the input field or visible options, review the result, then copy or download the output for the next step.
Private processing in your browser
Base64 File Converter — Encode & Decode Files Online Free keeps the normal processing step local in your browser. That is useful for code snippets, tokens, documents, configuration values, text samples, and other material that should not be sent to a remote service unless you explicitly choose to share it.
When this tool is useful
Use Base64 File Converter — Encode & Decode Files Online Free for repeatable developer tasks, technical documentation, QA checks, quick conversions, debugging, content cleanup, and internal team workflows. The page focuses on clear inputs, immediate feedback, and output that is easy to reuse in code, reports, tickets, emails, or notes.
Practical tips
Before copying the final result, check important details such as spacing, casing, filenames, encoding, token structure, line breaks, or output format. Small checks prevent mistakes when the result is reused in source code, API requests, documentation, spreadsheets, or shared files.