A Markdown table is the one people actually write by hand: pipes between the cells, a row of dashes under the header. GitHub, docs sites and half the world's READMEs render them, and their one real subtlety is that a pipe inside a code span is text, not a column break.
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 MD file above and choose afterwards.