Security

Base64 Batch

Free batch Base64 tool: paste a list of strings (one per line) and Base64-encode or decode every line at once. Invalid lines are flagged per line, not aborted. Runs in your browser.

YOUR WORKSPACEFree to use. No sign-up.

List of strings (one per line)

Mode

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Enter a list of strings above, then press Process All.

Deep dive guides

A LITTLE CONTEXT · 3 MIN READBase64 Batch Explained: Encode and Decode a Whole List at Once

All 2 related guides

How Base64 Encoding Works — Why every 3 bytes become 4 characters, what the = padding means, and why Base64 output runs about a third bigger than its input.
Base64 Batch Explained: Encode and Decode a Whole List at Once — Encode or decode a list of strings to Base64 in one pass: how the batch works, what the = padding means, and why one bad line doesn't sink the whole run.

How base64 batch works

This tool encodes or decodes every line in a list at once, so you can convert a whole column of strings to or from Base64 in one pass instead of processing them one by one. Each line is handled independently, and every output maps to the input line at the same position.

Pick a mode (encode or decode), paste one string per line, and the tool runs the standard Base64 transform on each line. Encoding converts text to a Base64 string; decoding reverses it. The transformation matches the single Base64 Encoder & Decoder.

If a single line cannot be decoded (for example, it is not valid Base64), that line is marked with an error but the rest of the list still processes. Empty lines are preserved and stay empty, so your line numbering never shifts.

Frequently asked questions

How is this different from the Base64 Encoder & Decoder?

The Base64 Encoder & Decoder handles a single string. This batch version takes a list of separate strings (one per line) and encodes or decodes each one independently, so a whole column of values comes out in one click.

What happens when a line is not valid Base64?

In decode mode, any line that is not valid Base64 is marked with a per-line error and produces an empty result, while the rest of the list still decodes normally. This lets you clean up a mixed list without it aborting halfway.

Can Base64 encode any text?

Base64 can encode any binary data. This tool routes each line through UTF-8 bytes first, so emoji and non-Latin scripts encode correctly (the browser's raw btoa only accepts Latin-1 and would crash). Decoding strips whitespace and accepts the URL-safe alphabet; a line whose decoded bytes are not valid UTF-8 text is reported per line rather than failing the whole batch.

What happens to empty lines?

Empty lines are kept in place and stay empty, so your line numbering is preserved and every input line maps to exactly one output line.

Base64 Batch

Processed lines

Deep dive guides

How base64 batch works

Frequently asked questions

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