Base64 編碼 / 解碼
對文字（UTF-8 安全）和檔案進行 Base64 編碼和解碼，並支援 URL 安全輸出。所有處理都在本地進行。
使用方法
Text is encoded as UTF-8, so non-ASCII text works as-is. The URL-safe option replaces + and / with - and _ and drops the = padding. To encode a file, just pick one (10 MB cap) — you also get a ready-made data URL. To turn Base64 back into a file, paste it into the input, set the MIME type and use the download button.
注意事項
Everything is processed in your browser; files are never uploaded. Decoding to text validates the result as UTF-8, so arbitrary binary data may fail with an error — use the download button for binary content instead.
常見問題
How much larger is Base64 output?
About 33%: every 3 bytes become 4 characters.
Can it decode Base64 with line breaks?
Yes, whitespace is ignored when decoding.