How to Track Polymarket Prices

All three share the UTC second, so a "price now" read and a "price at 14:42:50" read are the same kind of object — the difference is only which clock you ask.

The field you trade is the executable side (0.99/0.995 bunching, 98.6% of the time); the field you display is the mid; the field that protects you is the depth behind the price. A tracker that only draws mid is a tracker that shows a line that no one could have traded.

The venue's mid-price explainer and the one-sided pages are the same lesson in two formats: price without book context is a guess.

Pick a live 5-minute window, poll /book each poll interval, and store bid/ask/mid/depth with a UTC timestamp. At resolution, pull the same market's recorded history and join: the tracker just validated itself against the archive's stored truth.

That self-validation is the honest test of any PDK — a tracking setup that cannot be reconciled to recorded history is one you cannot trust.

Live polling over the free API is rate-limited and forward-only: snapshot locally if you need the past, because the live endpoint will not sell you yesterday. The archive exists precisely to cover that form of amnesia.

• Live odds
• Price history
• Alert tools