.txtz

File format · Released 2010 · By Calibre (Kovid Goyal)

About TXTZ Files

TXTZ eBook

TXTZ is a zipped plain text ebook format used by Calibre that packages a text file with optional metadata into a ZIP archive. It provides a lightweight ebook container when rich formatting is not required.

Family

eBooks

Extension

.txtz

MIME Type

application/txtz

Can Use As

Input Output

● Hex Magic-Bytes Signature (Offset 0x00) eBooks Binary/Text Stream

54 58 54 5A 00 01 00 00 4B 41 49 4A ASCII: TXTZ....KAIJ

Convert TXTZ → PDF → 15+ CONVERSIONS ↓

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Width ()

Height ()

Unit

Print Density (DPI)

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📈 Target Minimum File Size (Guaranteed ≥ KB)

Lossless JPEG Q100 + standard COM segment padding for government & exam portals

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The story

HOW TXTZ CAME TO BE.

TXTZ — zipped plain text — is HTMLZ’s even simpler cousin. An .txtz is a ZIP archive containing a .txt file plus optional metadata. Calibre uses TXTZ as an intermediate when converting ebooks to unformatted text with preserved metadata. It’s the absolute minimalist wrapping of a plain-text ebook.

ISO / MIME SPECS

Technical Specifications

MIME type: application/x-txtz
Extension: .txtz
Container: ZIP + TXT
Tool: Calibre

Typical Sizes & Weights

Novel (plain text)

200 KB - 1.5 MB

STRENGTHS & LIMITATIONS.

Strengths

Minimalist ebook wrapper.
Plain-text core.

Limitations

Niche.
No reader adoption.

CURIOSITIES & TRIVIA.

TXTZ is the minimum viable ebook format — a ZIP wrapping one text file.

Calibre defined TXTZ for converting ebooks where formatting doesn't matter.

Most .txtz files are unreadable by mainstream ebook apps — Calibre is the primary consumer.

Renaming .txtz → .zip gives you back the plain text file.

STUDIO TOOLS FOR TXTZ

Specialized Utilities for .TXTZ Files

View all 45 tools →

merge →

Merge PDF

Combine multiple PDF files into a single document. Drag and drop to reorder pages before merging. No software installation required.

split →

Split PDF

Split a PDF into separate files by page ranges or extract individual pages. Perfect for isolating chapters, invoices, or specific sections.

compress →

Compress PDF

Reduce PDF file size without visible quality loss. Choose from low, medium, or high compression levels. Ideal for email attachments and web uploads.

convert →

PDF to Word Converter

Convert PDF documents into editable Microsoft Word (DOCX) files online for free while preserving layout, tables, and typography.

convert →

Word to PDF Converter

Convert Microsoft Word documents (DOCX, DOC) into print-ready PDF files with exact font embedding and layout preservation.

convert →

PDF to Excel Converter

Extract tables, financial rows, and structured columns from PDF files directly into editable Microsoft Excel (XLSX) spreadsheets.

ocr →

Make PDF Searchable (OCR)

Add a searchable text layer to scanned PDF documents using OCR. The visual appearance stays the same but you can now search, select, and copy text.

decrypt →

Unlock PDF

Remove owner printing/copying restrictions and decrypt password-protected PDF files instantaneously once you enter the known password.

CONVERT FROM TXTZ

txtz pdf txtz docx txtz odt txtz txt txtz md txtz html txtz epub txtz mobi txtz azw3 txtz fb2 txtz rst txtz htmlz txtz pdb txtz lrf txtz snb

CONVERT TO TXTZ

epub txtz mobi txtz azw3 txtz fb2 txtz htmlz txtz pdb txtz lrf txtz snb txtz lit txtz cbz txtz cbr txtz

Common Use Cases

Plain text ebook distribution, Calibre workflows, minimal ebook format