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libheif is the free open-source library that reads and writes HEIF and AVIF images, published as source by its developers and available for Windows as a third-party build with command-line encode and decode tools included.
libheif is the library that reads and writes HEIF and AVIF images.
It is not a program you install and open.
It is a part that other software is built around.
If you arrived here wanting to view an iPhone photo on Windows, the section below points you somewhere better.
UPDATE THIS ONE
Version 1.23.4 fixes six security flaws, three of them rated high, and the developers advise everyone to take it. Anything still on 1.23.1 or earlier can be crashed, deadlocked or ground to a halt by a crafted image file.
What You Actually Download
The libheif project itself publishes source code only. No installer, no DLL, no executable, on any platform.
The Windows build offered here is a third-party one, compiled from that same source by an independent maintainer. For a plain download-and-run package of the command-line tools, it is effectively the only game in town.
WHERE THE WINDOWS BUILD COMES FROM
It is built from the official source by an independent maintainer rather than by the libheif project, and the release it is compiled from matches the upstream tag exactly. This time it landed two days after the source release, which is unusually quick - historically the Windows build has arrived weeks later and occasionally skipped a version.
What you get is more than a library. The archive carries five command-line tools alongside the DLL, and it is a genuinely usable HEIC and AVIF toolkit rather than something only a developer can open.
- heif-enc converts images into HEIC or AVIF, with quality and codec options.
- heif-dec converts the other way, out to JPEG, PNG, TIFF or WebP.
- heif-info reports what is inside a file - tracks, tiles, metadata, colour profile.
- heif-view displays an image, and heif-thumbnailer generates thumbnails.
It also bundles nearly every codec libheif can use - x265, aom, SVT-AV1, rav1e, dav1d, de265, x264, OpenH264, kvazaar and two JPEG 2000 libraries. That is why a library download unpacks to many times the size of the archive.
Unpack it anywhere and run the tools from a terminal. Nothing installs and nothing registers itself with Windows, so if you were expecting File Explorer thumbnails, the next section is what you actually want.
If You Just Want to Open HEIC Files
This is the right section for most people, and it is a two-minute job rather than a compile.
On Windows, install HEIF Image Extensions plus the HEVC Video Extension, and File Explorer and Photos start reading HEIC directly.
The second of those is the part that catches people out, because it is a paid Store listing. The guide on how to get the HEVC extension free covers the way around it.
If the Microsoft Store refuses to install either of them, the PowerShell fix when the Store fails is the workaround that does work.
For AVIF stills the equivalent is the AV1 Codec extension, which covers AVIF as well as AV1 video.
Several viewers skip Windows entirely and decode both formats themselves. ImageGlass and nomacs both open HEIC and AVIF with no system extension installed.
PicView does the same and is the lightest of the three.
What Is New in 1.23.4
This release, dated 6 September 2026, is almost entirely about security, and every one of the six flaws was found and reported by the same researcher. Three are rated high.
- A parser that could be made to crawl. A file could declare an unlimited number of items, and scanning their references then took quadratic time - one test file dropped from 1.83 seconds to 0.26 once the limit was enforced.
- A crash on chained images. The check for reference loops recursed without a bound, so a long chain of derived items brought the parser down; it now uses a list rather than recursion, and runs at decode time.
- A permanent decoder freeze. Two threads decoding grid tiles that referenced each other took their locks in opposite order and deadlocked forever - circular reference graphs are now rejected before decoding starts.
- Three medium fixes. An out-of-bounds read in the aom and x265 encoder plugins when luma and chroma bit depths differ, a memory leak in sequence sample reading that could not be reclaimed, and an out-of-bounds read in the experimental WebCodecs plugin.
There are useful bug fixes too. Encoding 10-bit input through x264 previously produced an 8-bit stream built from misread bytes, aom lossless encoding failed outright with a confusing error, and a file containing a reference loop no longer refuses to open as a whole - only the broken item inside it fails.
It is compatible with 1.23.3 at both the API and ABI level, so updating requires no code changes in anything built against it.
What the Library Can Do
On the decoding side it handles tiled images, alpha channels, embedded thumbnails, and EXIF and XMP metadata. It reads depth maps, multiple images per file, and the crop, mirror and rotate transformations stored in the container.
Progressive decoding lets an image be previewed while it is still downloading, and a plugin interface allows extra codecs to be added.
On the encoding side it writes lossy and lossless at adjustable quality, preserves transparency, embeds thumbnails and colour profiles, and supports 10-bit and 12-bit depth as well as monochrome.
Recent versions also read and write HEIF image sequences, which are close enough to MP4 that the library decodes many MP4 videos as a side effect.
Related Libraries and Tools
For AVIF specifically, libavif is the dedicated library, and the AOM AV1 Encoder is the reference encoder underneath a lot of AVIF work.
On Windows, WIC for HEIC and CopyTrans HEIC both add Explorer thumbnail support without going near a compiler.
IrfanView and JPEGView open both formats once the right extensions are in place.
For converting a folder at a time, XnConvert and iMazing Converter both batch HEIC and AVIF.
For a single file there is JPEG to HEIF and HEIF to JPEG in the browser.
Further Reading
- How to Open and View HEIF Images
- How to Open HEVC, HEIC and HEIF Files
- How to Uninstall HEVC and HEIF Extensions
Quick questions
Is the .tar.gz the Linux version?
No, it is the source code. The libheif project publishes no compiled binaries for any platform, so that archive is what you build from or what a Linux distribution packages.
Who builds the Windows version?
An independent maintainer, not the libheif project. It is compiled from the official source at the matching release tag, and the 1.23.4 build followed the source release by two days.
How do I install it on Windows?
You generally do not. Install HEIF Image Extensions instead, or use a viewer that decodes HEIC itself.
Is libheif free?
Yes, and open source. It is distributed under the LGPL, with the command-line tools under the MIT licence.
Should I be worried about the security fixes?
If you decode files from other people, yes - update. The six flaws fixed in 1.23.4 are denial-of-service rather than code execution, but a permanently deadlocked decoder is still a real problem in anything that runs unattended.
What is the difference between HEIF and AVIF?
The container is much the same; the codec inside differs. HEIF wraps HEVC-compressed images, AVIF wraps AV1, and AV1 is royalty-free where HEVC is not.
Can it convert my photos?
Its command-line tools can, but for a folder of images XnConvert is far less work.
The wider video codecs catalogue covers the decoders and extensions worth having alongside it.
Download libheif 1.23.4 for Windows and see how the tools handle your files, or tell us how you got on if you have used it before.
