A `. If you are you looking for more info in regards to TDDD format check out our own page. tddd` file has no documented specification and usually exists as a custom file tied to a certain application’s internal design, where developers create unique extensions to hold serialized information, configs, or temporary data readable only by their tools; game and simulation systems also use such extensions for storing scenes or debug snapshots, and sometimes the file is nothing more than a renamed format like text-based data or a binary package such as SQLite that becomes recognizable when opened in an editor.