Folders and flags
All messages
Nothing in this folder matches the filter.
Pick a message on the left and it opens here.
Univik Online The Bat! Viewer
100% private. Reads the file on this device
To open a TBB file, pick MESSAGES.TBB or a .tbk backup and it opens here in your browser, with no email client, nothing to install and nothing uploaded.
Or pick one from this device. The mail stays on your machine.
Most TBB viewers are Windows programs you must install first, and the online ones send your file to a server. Here your own browser reads the TBB file directly from your disk.
Nothing is sent and there is no server. Disconnect from the internet and it still works.
The Bat! from Ritlabs runs on Windows only and asks for a license once the trial ends. This viewer opens the same mail anywhere.
Nothing is written back to your file. Flags, raw headers and dates stay exactly as the mail client saved them.
Short answer: TBB and TBK files open here on Windows, Mac, Linux, ChromeOS, iPhone, iPad and Android. No mail client, no upload.
Edge or Chrome reads the mail directly, which helps if you moved to Outlook or Gmail and still keep old TBB files. For batch export use the Univik The Bat! Email Converter.
Ritlabs never made a Mac version, so nothing on a Mac opens a TBB file. Safari or Chrome reads it here.
Any Linux system with Firefox or Chromium, for when the old PC is gone and only the mail folder was kept.
ChromeOS cannot run Windows mail apps. Choose the file in Files or Drive and the list builds there.
Put the TBB file in Files or iCloud Drive, then tap Choose on this page in Safari.
Pick it from Downloads or Drive in Chrome, Samsung Internet or Firefox.
A TBB file is how The Bat! stores one mail folder: every message in that folder, saved one after another in a single file.
Ritlabs changed the index file from TBI to TBN in version 4.1, but the message base itself never changed. One reader covers version 1 through version 12.3, released July 2026.
A backup is packed down to save space, using zlib. The viewer unpacks it, checks each piece for damage and puts the folder names back.
Read and unread, answered, forwarded, parked and flagged are saved next to each message. The viewer shows them and filters the list by them.
Deleted mail stays in the file until you compact the folder, so the viewer shows it under its own filter.
HTML mail appears with its pictures in place, and a second tab shows the plain text. Pictures stored on a web server stay blocked until you ask.
PDF, Office, image and zip files are listed under their real names. Pictures preview in place, and a forwarded mail opens as its own message.
Before mail is sent it is often turned into odd-looking text, by MIME rules such as base64, quoted-printable or uuencode. The viewer turns it back. UTF-8, UTF-7, Windows-1251, KOI8-R and ISO-8859 all read correctly, so Russian, Japanese, Chinese, Korean and Greek mail is readable. A drop-down fixes the letters when a sender marked them wrongly.
A file that stopped copying, two mailboxes joined into one or corrupt data in the middle will still open. The viewer moves to the next real message.
A POP3 account gives every mail folder its own folder on disk. An IMAP account names its files 00DB7A9D.TBB and keeps the real names in ACCOUNT.FLB. The viewer reads that list, so your folder structure comes back with Inbox, Outbox, Sent Mail, Trash and Drafts named as they were.
Drag MESSAGES.TBB onto the box above, or pick several files at once. A .tbk backup, .msb export or .bck repair copy works the same way.
The list fills while the file is read. Filter by folder or flag, search a sender or subject, then click a message.
Switch between the message, the plain text and the raw headers. The Attachments tab previews a picture or saves any attached file.
Four kinds of file hold this mail, and the viewer reads all four.
Each mail folder holds MESSAGES.TBB with the mail and MESSAGES.TBN with the index. Pick the TBB file, not the TBN.
Made by Tools then Backup, or saved as autobackup.tbk.
A mail folder exported as one file, ready to import elsewhere.
Repairing a folder saves the old message base as MESSAGES.BCK. Missing mail can often be recovered from it, so open it and see what is there.
Univik makes both. Use this page to read mail on any computer or phone. Use the Univik The Bat! Email Converter when the mail has to come out as files you can keep or print.
| Feature | Online The Bat! Viewer | The Bat! Email Converter |
|---|---|---|
| Install needed | None at all | A Windows setup file |
| Operating system | Any system with a browser, phones included | Windows 11 and 10 |
| Files uploaded | Never, the file stays on your device | Never |
| Reads | TBB, TBK, MSB, BCK | TBB, TBK |
| Deleted messages left in the file | Listed and marked | Read as well |
| Saves messages out | Attachments only | PDF, PST, EML, MSG, MBOX, HTML and more |
| Large mailboxes | Read in pieces, so very large files open | No limit on size |
| Price | Free | Licenses from $29 |
Direct answers about reading a The Bat! message base in a browser, with no mail client and no license key.
No. This page holds the whole viewer. Your browser reads the message base from your own disk and builds the list itself. There is no server, and it works offline.
Load this page in any browser and drop MESSAGES.TBB onto the box near the top. The list appears in seconds, with no mail client, license key or download needed. There is no file size limit, so a mailbox of several gigabytes opens too, read in pieces as you go.
Look under AppData\Roaming\The Bat! in your Windows user folder. A POP3 account gives each mail folder its own folder on disk, holding MESSAGES.TBB. An IMAP account puts them under an IMAP folder. AppData is hidden, so turn on Hidden items in File Explorer's View tab.
Yes. Pick the .tbk file as you would a TBB file. A backup is packed down to save space, so the viewer unpacks it in your browser and rebuilds the mailboxes. One saved without packing opens too, and so does a plain zip of a mail folder.
Often yes. A deleted message is only marked as deleted. It is thrown out when you compact the folder, the clean-up job in The Bat!, so until then the text is still there. The viewer reads those messages and gives them their own filter. Once a folder has been compacted, the message is gone and no tool can recover it.
Some older mail carries the wrong encoding label, or none at all. The viewer reads the label first and guesses when it is missing. Every message also has an encoding menu next to the flags, with Windows-1251, KOI8-R, DOS-866, UTF-8, Shift_JIS, GBK and EUC-KR in the list. One choice usually corrects the text.
There is a setting that keeps attachments as normal files on disk instead of inside the message base. When it was on, the message here shows its text and headers while the attached files stay next to MESSAGES.TBB. Copy the whole folder rather than the TBB file alone. Those files then open from File Explorer.
Usually. If a copy stopped early, every message before that point reads normally. The last one is shown up to where the file stops, marked as cut short. If two mailboxes were joined, or the file is corrupt in the middle, the viewer looks for the next real message.
Notepad shows unreadable symbols with pieces of text between them, because a TBB file is not plain text. The mail client is not needed either. This page is the whole tool, with no add-on and no setup, which helps when a license has run out or the old PC is gone.
Free, with no message limit and no sign up. For forensic and evidence work it is as safe as opening the file on your own PC. It never leaves the machine, and it is only read, never changed. Raw headers, Message-ID and Received lines appear exactly as stored. For reports or bulk export, use the Univik The Bat! Email Converter.
Univik has made email and file conversion software since 2013, including the desktop The Bat! Email Converter. The same team wrote the reader behind this page.
The reader was checked against real mailboxes and .tbk backups from a working install, and against damaged files made on purpose. Version facts come from Ritlabs' own pages.
Free and private, with no setup at all. The mail never leaves your machine.
Choose a .tbb or .tbk file