Base64 Encode is a text transform, not a lock
Put a small piece of text or data into a channel that only allows plain ASCII.
The text you paste is encoded as Base64 in the browser. It is not uploaded.
Do not treat this as security
Base64 is not a password and not encryption. Do not paste secrets you would not also put in the page source.
Base64 Encode without the extra promises
Base64 Encode sits on this site because Text and Base64 are not interchangeable, even when they look similar in a file list. Put a small piece of text or data into a channel that only allows plain ASCII. Font conversions and developer utilities are paste boxes, not file uploads. Developers encode a small payload so a text API will accept it, or decode a payload they received.
The text you paste is encoded as Base64 in the browser. It is not uploaded.
Read this about Text before you upload
This tool works on text you paste. The text stays in the browser. The wrong input type produces the wrong output, and the page cannot guess which font you used.
Paste a copy. Keep the original document open beside it.
Read this about Base64 before you send the download
The download has to be Base64, because that is the format the next step named. Developers encode a small payload so a text API will accept it, or decode a payload they received. Any receiver can reverse Base64. That is the point.
Check padding and line breaks if a decoder rejects the string.
Keep, check, then delete
People lose time when they convert before they know which rule failed. Size, pixel dimensions, codec, font encoding, and layout are different rules. Base64 Encode only addresses the Text to Base64 step. Put a small piece of text or data into a channel that only allows plain ASCII. The text you paste is encoded as Base64 in the browser. It is not uploaded. Base64 is not a password and not encryption. Do not paste secrets you would not also put in the page source. The text stays in the browser. Try one line you can check before a whole document. Do not paste passwords. Do the test with a short or simple file first when the real file is large. A one-page PDF, a single photo, or a one-minute clip will show you whether the output is the kind of file you needed. After that test looks right, run the real file once. Keep both the Text original and the Base64 download until the receiving person or the upload form accepts it. Base64 Encode is a text transform for a payload you already understand. Encoding is reversible on purpose. It is not a lock, not a password store, and not a place for production secrets. Check the output before you paste it into a live request, and do not run the tool twice on text that was already encoded.
Here is the decision for Base64 Encode. You start with Text and you stop when a real program accepts Base64. Nothing is uploaded. You can try one line first. It is encoding, not encryption. Anyone who sees the text can reverse it. Do not hide passwords this way. If those two sentences describe a tradeoff you do not want, do not convert. Renaming the extension by hand will not do this job. Running the tool twice on its own output will not do it either.
Base64 is not a password and not encryption. Do not paste secrets you would not also put in the page source.
A related step, if you still need one, is Base64 Decode.
Other jobs start from the homepage, where each tool is named for the conversion it actually does.