What BZ2 to ZIP does with the archive
Older Unix archives use bzip2. Phones and Windows want ZIP.
The BZ2 is unpacked locally and saved as ZIP. bzip2 is slower than gzip, so a large file can sit for a while. Stay on the tab.
What still needs a desktop app
Password-protected files fail. If the result contains one .tar, that inner bundle may still need TAR to ZIP.
BZ2 to ZIP without the extra promises
BZ2 to ZIP sits on this site because BZ2 and ZIP are not interchangeable, even when they look similar in a file list. Older Unix archives use bzip2. Phones and Windows want ZIP. Phones and Windows want ZIP, not BZ2. ZIP is the file you send when you do not know what the other computer has installed.
The BZ2 is unpacked locally and saved as ZIP. bzip2 is slower than gzip, so a large file can sit for a while. Stay on the tab.
Read this about BZ2 before you upload
BZ2 is bzip2 compression. It is slower than gzip and still common on older Unix archives. Large files can sit for a while because bzip2 is slow. Stay on the tab. Password-protected files fail.
Keep the BZ2 until the ZIP shows the files you expected.
Read this about ZIP before you send the download
The download has to be ZIP, because that is the format the next step named. ZIP is the file you send when you do not know what the other computer has installed. RAR, 7Z, TAR, gzip, and bzip2 can be unpacked into ZIP here.
Open the ZIP and look at the file list before you delete the original.
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. BZ2 to ZIP only addresses the BZ2 to ZIP step. Older Unix archives use bzip2. Phones and Windows want ZIP. The BZ2 is unpacked locally and saved as ZIP. bzip2 is slower than gzip, so a large file can sit for a while. Stay on the tab. Password-protected files fail. If the result contains one .tar, that inner bundle may still need TAR to ZIP. The file stays in your browser and is not uploaded. The limit is 100 MB. Keep the original until the download has been opened in the program that will use it. 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 BZ2 original and the ZIP download until the receiving person or the upload form accepts it. Open the archive BZ2 to ZIP gives you before you delete the one you started with. Password-protected files fail. Some Unix downloads hide a TAR inside gzip or bzip2, so one conversion may not be the last step. ZIP is the file you can hand to a phone or a Windows PC without an extra app. Creating RAR or 7Z still needs a desktop program.
Here is the decision for BZ2 to ZIP. You start with BZ2 and you stop when a real program accepts ZIP. The archive can be unpacked locally and saved as ZIP. A ZIP of a PDF is not a meaningful compression of that PDF. Password-protected archives fail. 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.
Password-protected files fail. If the result contains one .tar, that inner bundle may still need TAR to ZIP.
A related step, if you still need one, is ZIP to 7Z.
Other jobs start from the homepage, where each tool is named for the conversion it actually does.