B64Bridge

Base64 Encoder / Decoder

Encode any text to Base64 or decode it back. Handles Unicode safely via UTF-8.

Plain text

Output

SGVsbG8sIHdvcmxkIQ==

Base64 encodings of common strings

Base64 maps every 3 bytes onto 4 ASCII characters, so encoded output is about a third larger than the input. Trailing = signs pad the final group.

Plain text	Base64
hello	aGVsbG8=
GintiCalc	R2ludGlDYWxj
Hello, World!	SGVsbG8sIFdvcmxkIQ==
admin:password	YWRtaW46cGFzc3dvcmQ=

Base64 is an encoding, not encryption: anyone can reverse it instantly. The admin:password row is exactly what HTTP Basic Auth sends, which is why Basic Auth is only safe over HTTPS. URL-safe base64 swaps + and / for - and _.

Why Base64 exists

Base64 packs arbitrary bytes into 64 printable ASCII characters. Used for embedding images in CSS/HTML, transmitting binary in JSON, and sending non-ASCII through systems that mangle special characters.

Frequently asked questions

I pasted an image into my HTML email and the file is huge — is that Base64?

Yes. Inline images in HTML emails are typically Base64-encoded, which increases data size by about 33%. A 100 KB image becomes roughly 133 KB of Base64 text. For large images, linking to a hosted URL is more efficient.

Is Base64 the same as encryption?

No. Base64 is encoding, not encryption — it transforms data into a portable ASCII format but provides zero security. Anyone can decode Base64 instantly. For actual secrecy, use AES or another cipher.

Why does my Base64 output end with = or ==?

The = padding characters appear when the input length isn't a multiple of 3 bytes. One leftover byte produces ==, two leftover bytes produce =, and a clean multiple of 3 produces no padding.

Can I Base64-encode binary files like PDFs or images?

Yes. Base64 can encode any binary data — PDFs, images, ZIP files. The tradeoff is a ~33% size increase. This is how email attachments work under the hood via MIME encoding.