How is this different from this site's text-based Base64 Encoder?

The string category's Base64 Encoder treats your input as UTF-8 text, which corrupts genuinely binary content like images or archives. This tool reads a real uploaded file as raw bytes with the File API, so it works correctly on any file type, not just text.

Does decoding always produce a valid file I can open?

It produces exactly the bytes the Base64 or hex text decodes to. Whether that's a valid, openable file of a particular type depends on whether the encoded text actually came from a real file of that type in the first place; this tool doesn't validate file format, only the encoding.

Is there a file size limit?

Yes, 25 MB, since the file is read entirely into memory and Base64-encoded on the main thread. Base64 also inflates size by about 33%, so very large files can produce a lot of output text.

Does this tool upload my file anywhere?

No. The file is read and encoded (or the text decoded) entirely in your browser; nothing is sent to a server.

Base64/Hex File Encoder & Decoder

Overview

Introduction

Base64-encoding a real binary file, an image, a PDF, an archive, by pasting it into a text-based encoder corrupts it, because that path assumes your input is text in the first place.

This tool reads an actual uploaded file's raw bytes and encodes them correctly, and decodes text back into a real downloadable file, entirely in your browser.

What Is Base64/Hex File Encoder & Decoder?

A real file-upload Base64/hex encoder and decoder: encoding reads a file with the browser's File API and converts its raw bytes to Base64 or hex text; decoding reverses that, turning pasted text back into a downloadable binary file.

It's the binary-safe counterpart to this site's text-based Base64 Encoder/Decoder tools, which are meant for text content, not arbitrary files.

How Base64/Hex File Encoder & Decoder Works

Encoding reads the selected file as an ArrayBuffer, then converts its bytes to Base64 (via a binary-string bridge to `btoa()`, chunked to avoid call-stack limits on large files) or to lowercase hex.

Decoding reverses either format: Base64 text is decoded with `atob()` back into raw bytes, and hex text is parsed two characters at a time into a byte array, then offered as a downloadable file.

When To Use Base64/Hex File Encoder & Decoder

Use it when you need to embed a real file's content as text, for a data URI, an API payload, or a config file, and a text-based encoder isn't safe for the binary content.

It's also useful for the reverse: reconstructing a real file from Base64 or hex text you've extracted from an API response, log, or embedded resource.

Often used alongside Base64 Encoder, Base64 Decoder and Bulk File Hash Generator.

Features

Advantages

Handles genuinely binary files correctly, since it reads raw bytes rather than assuming text content.
Supports both Base64 and hex output, covering the two most common text encodings for binary data.
Round-trips: encode a file, then decode the result, and get back the exact original bytes.

Limitations

Capped at 25 MB per file to keep everything in-memory and responsive in the browser's main thread.
Doesn't validate that decoded bytes form a well-structured file of any particular type, only that the text was valid Base64 or hex.

Examples

Encoding a small image file to Base64

Input

icon.png (1.2 KB)

Output

iVBORw0KGgoAAAANSUhEUgAA...

The file's raw bytes are read and converted directly to a Base64 string, suitable for embedding in a data URI or JSON payload.

Best Practices & Notes

Best Practices

Use hex output when you need a fixed-width, easily-diffable representation; use Base64 when you need the most compact text representation (about 33% smaller than hex for the same bytes).
Verify a round trip (encode, then decode the result) once when integrating with a new downstream system, to confirm nothing is being altered along the way (like whitespace being inserted into the Base64).
Remove or account for the `data:<mime-type>;base64,` prefix separately if you're extracting Base64 from a data URI; this tool expects the raw encoded text.

Developer Notes

Encoding converts the file's `ArrayBuffer` to a binary string in 32 KB chunks (via `String.fromCharCode(...)` on `Uint8Array.subarray()` slices) before calling `btoa()`, since spreading a very large typed array directly into `String.fromCharCode` can exceed the JS engine's maximum argument count. Hex decoding parses two hex characters at a time into a `Uint8Array` with `parseInt(..., 16)` per byte.