Convert TCX to CSV (spreadsheet)

Opening a TCX file directly in a spreadsheet is not really possible — it's nested XML, laps inside an activity inside a course, and no row-per-point layout to import. This tool flattens that structure: one row per trackpoint, with a header naming every column your file actually has data for. Unlike the TCX-to-GPX or TCX-to-KML conversions on this site, lap information isn't discarded here — TCX's lap boundaries survive as a lap_index column, incrementing by one each time a new lap starts in the source file. That's not the same as CSV having true lap objects with their own summary stats (CSV doesn't have that structure, so it's a lossy translation), but it means the lap boundary itself — which point started which lap — is fully recoverable from the data, which is often all a spreadsheet analysis actually needs; you can filter or pivot on that column the same as any other. Heart rate, cadence, and power carry over exactly since CSV has a column for anything TCX can produce. Temperature is the one channel that never makes the trip, but that's a TCX limitation, not something the CSV format drops — TCX has no temperature element to source it from in the first place. Timestamps gain millisecond precision in the CSV output, matched with an elapsed-seconds column for anyone who'd rather work in relative time than wall-clock time. Everything runs client-side in a background worker in your browser, so a multi-hour activity with a large point count converts without freezing the page, and the file itself is never sent anywhere to do it.