OpenTX 2.1.9 was released back in early 2016. You probably need it for one of three reasons:
If you are currently on an older version and are deciding what to do, here is the verdict: opentx 2.1.9 download
If you are coming from an even older firmware (like the stock FrOS), upgrading to 2.1.9 is a massive leap. Key features include: OpenTX 2
Former community member OpenTC maintains a legacy archive. This is useful if GitHub is blocked or slow in your region. However, always verify the MD5 checksum against the official GitHub hash to ensure the file is not corrupted. opentx 2.1.9 download