Mail archive reader (mbox and eml)
An .mbox file is how mail clients store a folder: every message of it, one after another, in a single file. A Gmail Takeout export is exactly that, and nothing on a normal computer opens it without installing a mail client and importing. This tool reads the archive in the browser — messages, senders, dates, attachments and a search across all of them.
A Gmail Takeout arrives as a .zip: unpack it, the mail is the .mbox inside. Thunderbird keeps its folders as files with no extension in the profile.
The archive is indexed and the messages are shown newest first, fifty at a time.
The search runs over senders, subjects and the text of every message at once.
A single message as .eml, all of them as an archive, or just the attachments.