ApSIC Xbench is a free QA tool that allows localization professionals to perform many checks typically available on full-fledged CAT/TEnT environments. One of the lesser-known features, however, is the ability to convert the main proprietary and open-source translation file formats to a TMX or a plain text file for further processing.
Here’s how you do it:
1. Download ApSIC Xbench
2. Select Project > New
3. Select a file type from the list and click on Add
4. Locate the file on your machine and hit Next
5. Then go to the Tools menu and select Export Items…
6. Tick the relevant boxes in the Filtering Section. Under Output choose TMX or TXT as the export file type and select the location of the export file. If you are exporting to TMX, you will also need to specify the source and target language pairs.
By the way, the tool also accepts SDLXLIFF files, so you could, for example, grab a bunch of these files, convert them to TMX and import them back to your main TM. To do so, in Step 3 above you would select XLIFF file, hit Next and then under Files of type choose All files (.*) under the dropdown menu.