Are my MKV files uploaded anywhere?

No. This conversion runs entirely inside your browser, so the file never leaves your device. You can confirm it yourself: open the network tab of your browser's developer tools and convert something. You will see the page load, plus the analytics and advertising the site is paid for with — and nothing carrying your file.

Is converting MKV to JXL free?

Yes. There is no account, no watermark and no limit on how many files you convert — it runs on your own machine, so it costs us nothing to let you. Files up to 100 MB are handled in the browser.

Does converting MKV to JXL lose quality?

No. JXL stores the same content without discarding anything, so the result is identical in quality to the original. One frame, at full resolution. A still from compressed video carries that compression — a fast-moving moment looks softer than a static one, which is the video’s own encoding rather than anything this conversion does.

Do I need to install anything to open JXL files?

No installation is needed for the conversion itself — it runs in the browser you already have. Opening the JXL afterwards needs whatever software normally handles JPEG XL on your device.

MKVtoJXL

Convert MKV to JXL

Up to 100 files at once. Mixed formats are fine.

You can convert MKV to JXL free and without an account: drop the file above and the JXL is ready to download in a second or two. The conversion happens inside your own browser, so the file is never uploaded — it works on Windows, Mac, Linux, iPhone and Android, and keeps working with the network switched off.

What MKV and JXL are for

An open container that holds anything — several audio tracks, subtitles, chapters. Weak on hardware players.

The JPEG successor. Can repack existing JPGs 20% smaller without touching image quality.

How to convert MKV to JXL

Drop your MKV file onto this page, or click to pick one.
Choose JXL as the target. The conversion runs inside your browser — the file is never uploaded.
Download the finished JXL file.

MKV vs JXL: what changes

MKV compared with JXL
	MKV	JXL
Full name	Matroska Video	JPEG XL
File extension	.mkv	.jxl
Media type	video/x-matroska	image/jxl
Compression	Lossy — file size is bought with quality	Either, depending on the setting

Quality: Nothing is lost. The result holds exactly the same picture, text or data as the original.
Where it runs: This conversion runs inside your browser. Your file is never uploaded, and it works with the network disconnected.
What can be lost: One frame, at full resolution. A still from compressed video carries that compression — a fast-moving moment looks softer than a static one, which is the video’s own encoding rather than anything this conversion does.

MKV to JXL: common questions

Are my MKV files uploaded anywhere?: No. This conversion runs entirely inside your browser, so the file never leaves your device. You can confirm it yourself: open the network tab of your browser's developer tools and convert something. You will see the page load, plus the analytics and advertising the site is paid for with — and nothing carrying your file.
Is converting MKV to JXL free?: Yes. There is no account, no watermark and no limit on how many files you convert — it runs on your own machine, so it costs us nothing to let you. Files up to 100 MB are handled in the browser.
Does converting MKV to JXL lose quality?: No. JXL stores the same content without discarding anything, so the result is identical in quality to the original. One frame, at full resolution. A still from compressed video carries that compression — a fast-moving moment looks softer than a static one, which is the video’s own encoding rather than anything this conversion does.
Do I need to install anything to open JXL files?: No installation is needed for the conversion itself — it runs in the browser you already have. Opening the JXL afterwards needs whatever software normally handles JPEG XL on your device.