.ttxt file: how to open it on Windows

2 Windows apps register the .ttxt extension. Install one of them to open the file with a double-click.

• 
  Subtitle Edit

  Subtitle Edit is a free and open source editor for video subtitles.

  Open source 5.3.0.0 96.1K ↓ ★ 14.7K
• 
  Aegisub

  Cross-platform advanced subtitle editor

  Open source 3.5.1 17K ↓ ★ 2K

Related guide: Change the default app for a file type in Windows