File Extension Guide📖 What is a DjVu File?
A DjVu file is a scanned document saved in a format built for exactly that job. The name is pronounced "déjà vu", and the file uses the .djvu extension, or sometimes .djv. It holds scanned pages, such as a book, magazine or manual, at a very small file size while keeping them sharp and readable.
The format was created at AT&T Labs, where a team including Yann LeCun, Léon Bottou and Yoshua Bengio worked on it from 1996, with the first version published in 1998 and the format settled by 2005. It was later marketed by LizardTech, and it is open source. Its whole reason to exist is fitting high-resolution scans into files far smaller than a PDF or TIFF.
You will meet DjVu most often with digitised books and archives. Libraries and book-scanning projects have long used it for ebooks, old manuals, newspapers and comics, because a scanned page in DjVu can be several times smaller than the same page in PDF.
Key Characteristics
- Built for scanned documents, not office files
- Very high compression, smaller than PDF or TIFF
- Open source, from AT&T Labs
- Has a text layer, so you can select and search
Common Uses
- Digitised books and ebooks
- Scanned magazines and newspapers
- Old manuals and catalogues
- Library archives of historical documents
⚡ Quick Facts
| File Extension | .djvu, also .djv |
| Full Name | DjVu, pronounced déjà vu |
| Category | Scanned document image |
| Developed By | AT&T Labs, later LizardTech |
| First Released | 1998, revised 2005 |
| Licence | Open source |
| MIME Type | image/vnd.djvu |
| Compression | Smaller than PDF, TIFF and JPEG for scans |
| Opens In | DjVuLibre, WinDjView, Sumatra PDF, Calibre |
| Related Extensions | .djv, .pdf, .tiff |
🧩 How DjVu Compression Works
The clever part of DjVu is how it treats a scanned page. Rather than saving one flat image, it splits the page into separate layers and compresses each in the way that suits it best.
Text Mask
A sharp, high-resolution layer for the text and line drawings, kept crisp so words stay readable.
Background
A lower-resolution layer for the paper and colour behind the text, where fine detail is not needed.
Searchable Text
An optional text layer from OCR, so you can select, copy and search the words like in a PDF.
Splitting the page this way, then using techniques like arithmetic coding and progressive loading, is how DjVu keeps a scan sharp while making the file far smaller than a single flat image would be.
💻 How to Open a DjVu File
A DjVu file does not open on its own, because most devices do not include a reader by default. You need a program that understands the format, and there are good free ones on every platform.
Install a reader
Get a DjVu reader such as the free DjVuLibre or WinDjView, or a viewer like Sumatra PDF that also opens DjVu.
Open the file
Launch the reader and open the DjVu, or drag the file into the window. It shows the scanned pages ready to read.
Read and search
Turn pages, zoom and, if the file has a text layer, select and search the text just as you would in a PDF.
🧰 The Best DjVu Readers
Several free programs open DjVu files. Some are dedicated to the format, others are general document viewers that handle it among many types.
| Reader | Platform | Cost | Notes |
|---|---|---|---|
| DjVuLibre DjView | Win, Mac, Linux | Free | The open-source reference reader |
| WinDjView | Windows | Free | Light and fast, Windows only |
| Sumatra PDF | Windows | Free | Opens DjVu, PDF and ebooks |
| Calibre | Win, Mac, Linux | Free | Ebook manager, also converts |
| Okular | Linux, Win | Free | KDE document viewer |
🔄 How to Convert DjVu to PDF
Converting to PDF is the usual way to make a DjVu easy to share, since almost every device opens a PDF. Univik's File Converter can turn a DjVu into a PDF.
With Calibre
Add the DjVu to Calibre, choose Convert and pick PDF as the output. It is free and works on Windows, Mac and Linux, though large files can be slow.
Print to PDF
Open the DjVu in a reader like WinDjView and print it to a PDF printer. This turns the pages into a PDF on any system.
Online converter
Upload the DjVu to an online converter and download a PDF, handy when you do not want to install anything. Avoid this for private documents.
You can also convert a DjVu the other way, into images. A converter renders each page to a JPG or PNG, which suits using a single page on the web. Keep in mind that DjVu compresses scans tightly for text, so images pulled out of one can look rougher than the original scan.
⚔️ DjVu vs PDF
DjVu and PDF overlap, but they were built for different things. DjVu is specialised for scans, while PDF is a general document format that everything can open.
| Feature | DjVu | |
|---|---|---|
| Scan compression | ✓ Excellent | ~ Good |
| File size for scans | ✓ Very small | ✗ Larger |
| Reader support | ✗ Niche | ✓ Universal |
| Image quality | ~ Lossy | ✓ Can be higher |
| Editing and forms | ✗ Few tools | ✓ Many tools |
In short, DjVu wins on file size for scanned pages, while PDF wins on compatibility, editing and sharing. That is why a common workflow is to keep a small DjVu archive copy but convert to PDF for everyday reading and sending.
🛡️ The Ransomware Warning
If a .djvu file will not open in any DjVu reader, and it appeared after a malware infection rather than from a book scan, it is likely an ordinary file such as a document or photo that ransomware has encrypted and renamed. It is not a real DjVu document.
In that case, a DjVu reader cannot help, since the contents are encrypted. The genuine fix is a security one. Emsisoft publishes a free decryptor for some STOP and Djvu ransomware variants, and keeping backups and up-to-date security software is the reliable protection.
🔀 Related Formats
DjVu sits among the document and scanned-image formats you compare it with or convert it to.
.djv | The same DjVu format with a shorter extension, used interchangeably with .djvu. |
.pdf | The universal document format, the usual target when converting a DjVu for sharing. |
.tiff | A high-quality scanned-image format, larger than DjVu but widely supported for archiving. |
.epub | A reflowable ebook format, an alternative for digital books meant for e-readers. |
.jpg | A common image format, larger than DjVu for a full scanned page. |
❓ Frequently Asked Questions
You need a program that reads the format, since most devices do not include one. Install a free reader such as DjVuLibre or WinDjView, or a viewer like Sumatra PDF that also opens DjVu, then open the file or drag it into the window. To read one without installing anything, an online DjVu reader opens it in a browser.
Every good DjVu reader is free. DjVuLibre is the open-source reference reader for Windows, Mac and Linux, WinDjView is a light option for Windows, and Sumatra PDF opens DjVu alongside PDF and ebooks. On Linux, Okular handles it. For a quick read with nothing installed, use an online DjVu reader in your browser.
Open the DjVu in a tool that can export PDF and save it out. Calibre converts DjVu to PDF for free on any platform, and you can also open a DjVu in WinDjView and print it to a PDF printer. Online converters do it in the browser with nothing installed. Expect the PDF to be larger, since DjVu compresses scans very tightly.
For most people DjVuLibre DjView is the best choice, since it is free, open source and works on Windows, Mac and Linux. WinDjView is a great light option on Windows, and Sumatra PDF is handy if you also read PDFs and ebooks. Calibre is best when you also want to convert the file to another format.
DjVu is specialised for scanned documents and compresses them far smaller than PDF, so a scanned book in DjVu can be several times smaller. PDF is a general document format that every device opens, with far more editing and form tools. DjVu wins on file size for scans, and PDF wins on compatibility and everyday use.
Usually because no DjVu reader is installed, which a free program like DjVuLibre fixes. If the file still will not open in any reader and it appeared after a malware infection, it may not be a real DjVu at all. A ransomware family called STOP, or Djvu, renames encrypted files with a .djvu ending, and those need a security fix rather than a reader.
A normal DjVu file is a harmless scanned document. However, the STOP or Djvu ransomware renames the files it encrypts with a .djvu extension, so a .djvu that came from an infection is an encrypted ordinary file, not a document. If you suspect that, a DjVu reader will not open it, and Emsisoft offers a free decryptor for some STOP and Djvu variants.
It separates a scanned page into layers, a sharp high-resolution mask for the text, a lower-resolution background for the paper and colour, and an optional searchable text layer. Each layer is compressed in the way that suits it, then techniques like arithmetic coding shrink the result. This is why a DjVu scan can be several times smaller than the same page as a PDF or TIFF.
Yes. DjVuLibre DjView runs on macOS, and dedicated Mac readers such as MacDjView open the format too. Calibre works on Mac for both reading and converting. If you would rather not install anything, an online DjVu reader opens the file in a browser, or you can convert it to PDF and read it in Preview.
Yes, with a reader app. On Android, ebook and document apps that support DjVu, such as FullReader, open the file. On iPhone, a DjVu reader app from the App Store does the job. On either, converting the DjVu to PDF first also works, since every phone opens a PDF without extra software.
Often yes. Many DjVu files include a text layer created by OCR, which lets you select, copy and search the words just like in a PDF. Whether it works depends on the file, since the text layer is optional. If a DjVu has only the page images and no text layer, the words are pictures and cannot be searched until the file is run through OCR.
Less than it once was, but it is far from gone. Before PDF became the standard for scanned documents in 2008, DjVu was the leading way to share scanned books online. It is still common in library archives and book-digitisation collections, where its small file size matters, though most people now convert DjVu to PDF for everyday reading.
Use a converter that renders each page to an image. Calibre, a dedicated DjVu tool or an online converter can turn a DjVu into a JPG or PNG per page. This is useful when you want a single page as a picture for the web. Note that DjVu compresses scans tightly for text, so an image taken out of a DjVu can look rougher than the original scan.
If the DjVu has a text layer from OCR, you can select and copy the text straight from a reader like DjVuLibre, or the tool djvutxt pulls the text out to a plain file. If the file has only page images and no text layer, the words are pictures, so you first run the DjVu through OCR software to recognise the text before you can extract it.
Not directly, since Kindle and most e-readers do not open DjVu. Convert the file first, to PDF for a page-faithful copy, or to EPUB or MOBI if you want reflowable text. Calibre handles these conversions and can send the result to a Kindle. A scanned DjVu converted to PDF keeps the original page layout, which suits reading on an e-reader.
📝 Summary
A DjVu file is a scanned document in a format built for the job, saved with the .djvu extension. Created at AT&T Labs and open source, it separates a page into layers and compresses them so tightly that a scan is often several times smaller than a PDF, which is why it is common for digitised books and archives. Open one with a free reader like DjVuLibre, WinDjView or Sumatra PDF, or an online reader, and convert it to PDF with Calibre when you need to share it widely. One caution worth knowing is that the STOP or Djvu ransomware also renames encrypted files with a .djvu ending, so a .djvu that will not open and came from an infection is a security problem, not a document.