Overview
Paste a Base64 string or data URI to decode it into its actual bytes, then see each byte rendered as an 8-bit, zero-padded binary group. This is a genuinely different operation from Base64-decoding to text: decoding first produces a `Uint8Array` of raw bytes, and each byte in that array becomes its own binary group - correctly handling any decoded content, including multi-byte UTF-8 sequences, rather than converting character codes one at a time (which silently breaks the instant a decoded character spans more than one byte). Useful for teaching or debugging exactly what bytes a Base64 string represents at the bit level. Runs entirely client-side; nothing you paste is ever uploaded.
Best for: Seeing the exact bytes a Base64 string decodes to, at the bit level
How to use this tool
- Paste Base64 or a data URI. A data URI prefix is stripped automatically if present.
- Decoded to raw bytes. The Base64 string is decoded into a Uint8Array of actual bytes, not characters.
- Each byte becomes binary. Every byte is rendered as an 8-bit, zero-padded binary group, space-separated.
- Copy the result. Grab the full binary string with one click.
Why use this tool
Byte-aware, not character-aware
Decodes to real bytes first, so multi-byte UTF-8 content in the decoded data converts correctly.
Data URI support
Paste a full data URI and the base64 payload is extracted automatically.
Clear errors on invalid input
Malformed Base64 is flagged immediately instead of producing garbled output.
Nothing leaves your browser
Decoding happens entirely client-side.
Frequently asked questions
The Base64 Decoder outputs the decoded content as readable text. This tool outputs the decoded content’s raw bytes as binary (8 bits per byte) - useful when you need to see the actual bit-level representation rather than the text it happens to spell out.
Converting per-character code points instead of per-byte silently breaks on any decoded content containing multi-byte UTF-8 sequences, since a single character can span more than one byte. Decoding to a byte array first and converting each byte guarantees a correct result regardless of what the Base64 encodes.