FVC Free Online Video Merger is the most efficient video joiner to help you combine MKV files free online. Within 3 steps, you can get a complete MKV movie file with subtitles in order.

1. Join two or more MKV files into one with simple three steps free online.
2. Use all the functions including joining MKV files without downloading any software.
3. Support various input and output formats including MKV movie files.
4. Uploaded files will be deleted within 24 hours to protect your privacy.

Step 1: Open FVC Free Online Video Merger and click the Upload Files to Merge button to launch the plugin, and then click the button again to choose the MKV files you want to merge.

Step 2: Click the insert new button to choose other MKV files. Then choose 1920x1080 resolution to keep high quality and choose the original MKV format to retain the original encode, which will ensure the subtitles play well.

Step 3: Click the Merge Now button and choose the desired folder to save.

Reading more: https://www.free-videoconverter.net/video-editing/join-mkv/