SubRip subtitles: a number, a timestamp, a line of text, a blank line, repeat. That's the entire format. It carries no styling and no positioning, which is precisely why every player, TV and video tool on earth reads it.

Every conversion below runs in this page, on your own machine. Nothing is uploaded, there is no queue, and there is no account to make. Pick a target format, or just drop a SRT file above and choose afterwards.