| lbr | LU Library Archive |
| lcb | Living Cookbook Backup |
| lg | Arhangel Compressed Archive |
| lgu | LG Windows CE Device Firmware Update |
| lha | LH ARC Archive |
| lhw | LhWarp Compressed Archive |
| liz | Liberty Instruments LAUD Program Update |
| lja | ljArchive Archive |
| lks | Liberkey Installation Package |
| lnx | Commodore 64 Lynx Archive |
| lok | WinGuard Pro Lok Archive |
| lou | Liquidware LouZip Archive |
| lpk | Lazarus Package |
| lpkg | Liferay Package |
| lqr | Squeezed LBR Archive |
| lrp | Linux Router Project Package |
| lrz | Long Range Zip Compressed Archive |
| lz | Lzip Compressed File |
| lz4 | LZ4 Compressed Data |
| lzb | LZB Archive |
| lzg | LZG Compressed Data |
| lzh | LH ARC Archive |
| lzip | Lzip Compressed File |
| lzj | Atari Jaguar LZSS Compressed Data |
| lzm | Slax Module |
| lzma | LZMA Compressed File |
| lzo | LZOP Compressed File |
| lzop | LZOP Compressed File |
| lzr | Crunched LBR Archive |
| lzss | LZSS Compressed Data |
| lzw | LZW Compressed Amiga Archive |
| lzx | Amiga LZX Compressed Archive |
| m | Mathematica Package |
| mabk | Lenovo MOTO Smart Assistant Backup Data |
| maff | Mozilla Archive Format File |