Base64 converter

Encode text or files and decode Base64 into the original bytes.

Encode and decode Base64

Convert UTF-8 text or file bytes to Base64, or decode Base64 to the original bytes. Everything runs in this browser.

Choose a binary file to encodeText to encode or Base64 to decode

ConversionAlphabet

Ignore ASCII whitespace when decodingOff by default. When enabled, only spaces, tabs, CR, LF, vertical tabs and form feeds are ignored. Other characters are rejected.

File or UTF-8 input: up to 2 MiB. Base64 input: up to 4 MiB including whitespace; decoded output: up to 2 MiB. Preview: 8,000 characters.

Standard output uses required = padding; URL-safe output has no padding. Standard decoding requires the required padding. URL-safe decoding accepts correctly padded or unpadded input. Mixed alphabets, data: prefixes, invalid padding and nonzero unused bits are rejected. Base64 is encoding, not encryption.

Files are encoded byte for byte, including BOMs and line endings. Pasted text uses the current browser text value encoded as UTF-8; earlier encoding or CRLF bytes may already have changed. Decoded .bin downloads preserve all bytes, including BOMs and line endings. Previewed HTML/SVG is plain text and never rendered.

Choose a file or enter text, select a conversion, then press Convert.

Result preview

Download complete result

Encode the example and recover its text

Try an example loads a greeting with Korean, Español and 😀, then encodes it with the standard alphabet. The preview is Base64 text. Downloading this encoded result saves a .base64.txt file, not the original greeting.
Copy the complete Base64 from this short example preview, paste it into the input, select Decode Base64 and keep Standard selected, then Convert. The UTF-8 preview should show exactly the greeting loaded by the example. The decoded download is .bin and contains those UTF-8 bytes, even when they are readable text.
Load the example again, choose URL-safe and Convert. Where present, + and / become - and _, and the trailing = padding disappears. Paste that result and decode with URL-safe selected to recover the same greeting. Changing the alphabet does not encrypt the content or create a share link.

To try a binary result separately, paste /w==, select Decode Base64 with Standard and Convert. It decodes to one byte, FF, which is not valid UTF-8 text. An unavailable text preview is expected; the .bin download still contains that byte.