gettext/PO is just as deficient at modern plural forms support as ResX, out of the box. The only format that I'm aware of that is specifically built to include

gettext/PO is just as deficient at modern plural forms support as ResX, out of the box. The only format that I'm aware of that is specifically built to include it as first-class is Mozilla's Fluent. The same workarounds generally apply to ResX as to PO: create a number of separate strings and do a bit of math up front to choose the right one, or use a formatter on top of PO/ResX that supports something like ICU MessageFormat. I found an attempt at doing Fluent in .NET: https://github.com/blushingpenguin/Fluent.Net/ https://github.com/blushingpenguin/Fluent.Net/ I also found at least one library for supporting ICU MessageFormat in .NET: https://github.com/jeffijoe/messageformat.net https://github.com/jeffijoe/messageformat.net