When you use WhatsApp's built-in Export Chat feature, the result is a compressed archive - a .zip file - that contains your conversation in a portable, self-contained format. Most people know the file exists but have never looked inside it. Understanding the structure of the ZIP helps you work with the export more effectively, whether you are converting it to PDF, submitting it as evidence, or simply archiving it for your own records.
What's in a WhatsApp ZIP File
A WhatsApp ZIP exported with media contains two types of content: one plain-text transcript file and a flat collection of media files. There are no sub-folders - everything sits at the root level of the archive. The exact number of files depends on how many images, videos, and audio messages were exchanged in the chat.
- _chat.txt - the full text transcript of the conversation, one message per line, in chronological order.
- Image files - saved as .jpg or .webp, named using WhatsApp's internal naming convention.
- Video files - saved as .mp4, typically compressed by WhatsApp at time of send.
- Audio messages - saved as .opus files (voice notes recorded inside WhatsApp) or .mp3/.m4a for forwarded audio.
- Documents - PDFs, DOCX files, or other documents shared in the chat, in their original format.
- Sticker files - saved as .webp with transparent backgrounds.
If you exported without media, the ZIP contains only _chat.txt - and in some cases WhatsApp skips the ZIP entirely and produces a bare .txt file. Both formats are fully supported by WaChat to PDF.
The _chat.txt File Explained
The _chat.txt file is the backbone of the export. Every message, system notification, and media reference is recorded here as a single line of plain text. The file is UTF-8 encoded and opens in any text editor, though it is not designed to be human-friendly at scale - a year-long active group chat can run to hundreds of thousands of lines.
Each message line follows the pattern: timestamp, sender name, colon, message body. The timestamp format varies between iOS and Android, and between 12-hour and 24-hour regional settings. A typical iOS line looks like: [05/03/2025, 10:14:33] Alice: See you at 3. A typical Android line omits the brackets and may use a different date separator. Parsers like the one in WaChat to PDF handle both variants automatically.
System messages - such as 'Alice added Bob' or 'Messages and calls are end-to-end encrypted' - appear on their own lines without a sender name. These are distinct from regular messages in the parser and are rendered differently in the PDF output.
Media Files in the ZIP
WhatsApp names media files using a consistent pattern: a zero-padded sequence number, a type label (PHOTO, VIDEO, AUDIO, DOCUMENT, STICKER), a date stamp, and a sequential counter. For example: IMG-20250305-WA0012.jpg or PTT-20250305-WA0003.opus. The PTT prefix stands for push-to-talk and identifies voice notes.
Each media file name that appears in _chat.txt corresponds exactly to a file in the ZIP archive. The converter matches them by filename, which is why you must upload the complete ZIP rather than just the _chat.txt when your chat contains media. Uploading only the text file results in placeholder cards appearing wherever a media attachment would be.
iOS vs Android ZIP Differences
The ZIP structure is broadly the same on both platforms, but there are a few differences worth knowing. On iOS, the ZIP is often named after the contact or group and the export date - for example, WhatsApp Chat with Alice.zip. On Android, the filename typically uses the format WhatsApp Chat - Alice.zip or a similar pattern depending on your Android version and manufacturer.
The more meaningful difference is inside _chat.txt. iOS exports use a day/month/year date format with a comma and a 24-hour or 12-hour time depending on your region. Android exports use a slightly different separator and sometimes omit the leading zero from day and month numbers. Some Android manufacturers also produce a format with a period as the date separator. WaChat to PDF's parser recognises all common variants.
If you are unsure which format your export uses, open _chat.txt in a text editor and look at the first few lines. The timestamp pattern will be immediately obvious. You can also upload the file directly to WaChat - the parser will auto-detect the format and flag any lines it cannot read.
What to Do with the ZIP File
The raw ZIP is not a useful end product for most purposes. It cannot be emailed as a readable document, attached to a court filing, or shared with someone who does not know how to extract it. Converting it to a well-formatted PDF preserves all the content - text, timestamps, sender names, and embedded media - in a format that anyone can open, print, and reference.
WaChat to PDF accepts the ZIP file directly. You do not need to extract it first. The converter reads _chat.txt and matches every media reference to the corresponding file in the archive, then generates a paginated PDF with WhatsApp-style chat bubbles, precise timestamps, and optional features like redaction and Bates numbering for legal use.
Ready to convert your WhatsApp ZIP? Upload it now and get a professionally formatted PDF in seconds - free for chats under 5,000 messages.
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