Translation guide
Describes a system or product that works with older versions or previous standards.
This software is backward compatible, so you can open old files.
Shorter, more direct way to say 'is backward compatible'. Common in product descriptions.
The new version is backward compatible.
Literally 'has lower compatibility', often used interchangeably with 後方互換性. Slightly more common in some technical contexts.
This standard is backward compatible, so older products can still be used.
More descriptive: 'compatible with old versions'. Useful when you want to be explicit.
This app is backward compatible, so you can update without worry.
Describing the act of ensuring backward compatibility during development.
Both are widely used. 後方互換 (backward compatibility) is more literal, while 下位互換 (lower compatibility) is common in IT. In most contexts they are interchangeable, but 後方互換 is slightly more formal.
We need to ensure backward compatibility in the new system.