Base64 To File Decoder

No. Your Base64 string is never sent to our servers - all decoding, MIME detection, preview rendering, and hex dump generation happens directly in your browser on your device using JavaScript.

Both raw Base64 strings and full data URIs (e.g. data:image/png;base64,...) are supported. Whitespace and line breaks inside the Base64 payload are stripped automatically before decoding, so wrapped or formatted strings work fine.

The decoder sniffs the first bytes of the decoded data against known magic byte signatures - PNG, JPEG, GIF, WebP, PDF, ZIP, MP3, and MP4 are detected this way. If no signature matches, the MIME type falls back to application/octet-stream and the file is treated as raw binary.

The Base64 input is capped at 50MB of text. That decodes to roughly 37MB of binary output. If the input exceeds this limit you will see an "Input exceeds the 50MB limit" error before decoding starts.

Images (PNG, JPEG, GIF, WebP, SVG) render inline as an <img> tag, audio plays in an <audio> control, video plays in a <video> control, PDFs render in an embedded iframe viewer, and text or JSON is displayed in a monospace pre block (first 2000 characters). Anything else is shown as a binary placeholder and can still be downloaded.

Yes. Click "Load from file" to import a .txt, .b64, .base64, or .pem file - the contents are read locally with FileReader. You can also drag and drop a file directly onto the tool to load it.

No. The current Base64 input and filename are saved to your browser's IndexedDB and restored automatically when you reopen the tool. Click Clear to wipe the input, the preview, and the persisted data immediately.

Edit the Filename field to whatever you like. If your filename has no dot, the tool auto-appends the correct extension (.png, .jpg, .gif, .webp, .svg, .pdf, .txt, .html, .css, .json, .zip, .mp3, or .mp4) based on the detected MIME type. If your filename already contains a dot, it is left untouched.

Paste a full data URI like "data:image/png;base64,..." and the tool automatically extracts the MIME type from the prefix and decodes the payload that follows. The MIME type from the data URI is trusted directly and used for both the preview renderer and the auto-extension.

Plain Base64 strings without a data URI prefix work too. Whitespace, tabs, and line breaks inside the payload are stripped automatically before decoding, so wrapped, indented, or multi-line Base64 from emails and config files just works.

When no data URI prefix is present, the decoder sniffs the first bytes of the decoded data against known signatures and detects PNG, JPEG, GIF, WebP, PDF, ZIP, MP3, and MP4 automatically. If no signature matches, the type falls back to application/octet-stream and the file is treated as raw binary.

PNG, JPEG, GIF, WebP, and SVG decode into a blob URL and render as an inline <img> tag inside a bordered preview panel, scaled to fit a max height of 320px. The original resolution is preserved in the downloaded file.

audio/* MIME types render in a native <audio controls> player so you can play the decoded MP3 or other audio file directly in the browser before downloading - useful for verifying TTS output and audio API responses.

video/* MIME types render in a native <video controls> player. MP4 files decoded from Base64 can be scrubbed and played back without leaving the page.

application/pdf decodes into a blob URL and renders inside a 500px-tall <iframe>, giving you a scrollable preview of the entire document so you can verify the right PDF before downloading.

text/* and application/json MIME types decode through a TextDecoder and display in a monospace pre block (first 2000 characters) with a Copy text button for quickly grabbing the decoded contents.

Toggle Show Hex Dump to view the first 512 bytes of the decoded file in a classic offset / hex / ASCII three-column layout. Each line shows an 8-digit offset, two groups of 8 hex bytes, and the printable ASCII characters - ideal for verifying magic bytes and inspecting binary headers.

After decoding, a horizontal info bar shows the detected MIME type, the current file extension (or em-dash if none is set yet), and the exact decoded file size formatted as B, KB, or MB so you know what you are about to download.

As you type or paste, the tool shows the cleaned Base64 character count and an Output: ~size estimate of the decoded binary, so you can spot oversized payloads before clicking Decode.

Drag any .txt, .b64, .base64, or .pem file directly onto the tool. A highlighted overlay appears while dragging and the file is read locally with FileReader.readAsText - the contents replace the textarea instantly. Nothing is uploaded.

Click "Load from file" next to the textarea to open a file picker scoped to .txt, .b64, .base64, and .pem extensions. The selected file is read locally and loaded into the input.

Click the Paste button to read Base64 directly from your system clipboard via the Clipboard API - faster than focusing the textarea and pressing Ctrl+V, especially on long payloads.

Type any name in the Filename field (default: decoded-file). If your filename has no dot, the correct extension is auto-appended based on the detected MIME type for 13 supported formats: .png, .jpg, .gif, .webp, .svg, .pdf, .txt, .html, .css, .json, .zip, .mp3, .mp4. If the filename already contains a dot it is left untouched.

Base64 inputs up to 50MB of text are accepted (roughly 37MB of decoded binary). Oversized inputs are rejected before decoding with a clear "Input exceeds the 50MB limit" error so the browser tab does not freeze on huge payloads.

Your current Base64 input and filename are saved to your browser's IndexedDB and restored automatically on the next visit. Refreshing the page or closing the tab will not lose your work. Click Clear to wipe the input, preview, and persisted data immediately.