Compress JXL Online

1. Upload one or more JXL files (up to 50 MB total).
2. Choose a mode: Lossless (no quality loss) or Lossy (bigger reduction).
3. Click 'Compress JXL' — finishes in under 5 seconds per image.
4. Download compressed JXL files, or grab all as a ZIP.

JXL is unique in offering both lossless and lossy compression in the same format. Lossless mode preserves every pixel while still shrinking the file; lossy mode achieves bigger reductions at the cost of quality.

JXL is one of the most efficient image formats available, but files can still benefit from further compression. Two modes are useful: (1) Lossless mode re-encodes at maximum compression efficiency without changing a single pixel — great for archival and design masters. (2) Lossy mode reduces quality from 100% to 80-90%, typically achieving 30-60% smaller files with no visible difference on modern screens.

The compressor decodes the JXL image and re-encodes it using libjxl. Lossless mode uses modular encoding with maximum efficiency — every pixel preserved. Lossy mode uses VarDCT with a lower quality setting. JXL's encoding is the most efficient of any mainstream format, so even lossy compression produces very small files.

• Compressing archival JXL masters with zero quality loss.
• Reducing JXL file size for storage optimization.
• Preparing JXL images for long-term archival.
• Shrinking JXL libraries for efficient backup.
• Reducing JXL file size before sharing with colleagues.
• Preparing JXL assets for delivery systems with size caps.
• Final optimization pass on JXL image libraries.

Lossless JXL compression preserves every pixel — the file is smaller, but the pixels are identical. Lossy JXL at 85-90% quality is visually indistinguishable from 100%. Below 70% quality, artifacts start showing. Because JXL is already efficient, compression gains are typically 30-60%.

• Very old software may not support JXL (Chrome removed support in 2023).
• AV1 encoding is CPU-intensive — 3-5 seconds per image.
• Below 70% quality, visible artifacts may appear.
• Animated JXL sequences are compressed using the first frame only.
• HDR metadata may be lost at lower quality settings.

• JXL opens in Firefox, Safari (via OS support), and some viewers.
• Native support in GIMP 2.10+, Krita 5+, and Adobe via plugin.
• Chrome removed JXL support in 2023.
• Windows 11 supports JXL with the free extensions.
• Best for archival and storage optimization.

• Use lossless mode for archival masters — no quality loss.
• Use lossy at 85% quality for general delivery — 30-50% smaller with no visible change.
• JXL is already efficient — savings are 30-60%, not 90%+.
• Batch-compress up to 50 MB of JXL files at once.
• Keep the original if the JXL is a critical asset.

JXL compression is slow

JXL encoding is CPU-intensive. Typical compression is 3-5 seconds per image. This is the trade-off for the most efficient compression.

JXL is barely smaller after compression

JXL is already efficient — savings are 30-60%, not 90%+. Try lossy mode or lower quality settings.

Lossless mode is slower than expected

Lossless JXL uses maximum-efficiency modular encoding, which is slower. For faster results, use lossy mode.

• JPEG XL — Official Specification