What is an FDT file?
The .FDT file extension has multiple meanings. The most common format is the Apache Lucene Index Field Data File used for search indexing by Apache Lucene. Another common format is the Final Draft 5-7 Template used by the screenwriting software Final Draft. Other specialized uses include data logs from Fuji Electric paperless recorders, Microsoft Visual FoxPro memo files, and EEG medical signal data.
How to open FDT files?
Because the .FDT extension is shared by many different applications, opening it depends entirely on the file creator. You might need Apache Lucene, Final Draft, or proprietary equipment software like Hitachi FL Spectrophotometer. Instead of guessing the correct software, viewer.online/fdt can analyze .FDT files to identify the exact format and creator software, inspect the file structure, extract readable text, and check whether an online preview is available.
Best practices and troubleshooting
Do not rename the .FDT file extension. This action does not change the actual file type. If you need a different format, we recommend converting your files using convert.guru. For example, you can convert a Final Draft 5-7 Template to a modern .FDX or .PDF format. If your file is a database or medical log, conversion might not be possible without the original software.
Summary
Using viewer.online/fdt is useful for identifying, inspecting, and understanding .FDT files without installing software or dealing with compatibility problems.