{"product_id":"measure-polymarket-slippage-with-n8n-form-polyorderbooks-api","title":"Measure Polymarket Slippage with n8n Form + Polyorderbooks API","description":"\u003ch3\u003eMeasure Polymarket Slippage with an n8n Form + PolyOrderbooks API\u003c\/h3\u003e\n\u003cp\u003eWant to know how a market buy would \u003cem\u003eactually\u003c\/em\u003e fill near settlement? This n8n workflow lets you enter a Polymarket market slug and buy size, then pulls 1-second order book snapshots from the PolyOrderbooks API to simulate the fill price and calculate slippage versus the midpoint—using the minutes leading up to close.\u003c\/p\u003e\n\n\u003ch3\u003eWhat this workflow does\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCollects inputs via an n8n form:\u003c\/strong\u003e market slug, number of shares to buy, and how many minutes before close to analyze.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFetches market timing from PolyOrderbooks:\u003c\/strong\u003e calls the \u003cstrong\u003ePolyOrderbooks API\u003c\/strong\u003e to retrieve market details and the market end time.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBuilds a back-from-end time window:\u003c\/strong\u003e constructs the analysis window starting at (market end time − your selected minutes) to the end time.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePulls order book snapshots:\u003c\/strong\u003e retrieves \u003cstrong\u003e1-second resolution\u003c\/strong\u003e order book data for the chosen time window.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSimulates execution across snapshots:\u003c\/strong\u003e walks the order book ask ladder to compute the average fill price, total cost, and \u003cstrong\u003eslippage vs midpoint\u003c\/strong\u003e.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eAggregates outcome stats:\u003c\/strong\u003e reports how often the buy is unfillable, plus the \u003cstrong\u003emedian\u003c\/strong\u003e and \u003cstrong\u003eworst slippage\u003c\/strong\u003e per outcome with a timestamp.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eUse cases\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eOperators and traders who want \u003cstrong\u003erealistic execution cost estimates\u003c\/strong\u003e for a Polymarket market buy near settlement.\u003c\/li\u003e\n  \u003cli\u003eSaaS teams building decision tooling around \u003cstrong\u003emarket liquidity and slippage risk\u003c\/strong\u003e.\u003c\/li\u003e\n  \u003cli\u003eAutomation engineers testing how order book depth changes as a market approaches close.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eTechnical details\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eNodes\/tech stack:\u003c\/strong\u003e \u003cem\u003eform trigger\u003c\/em\u003e, \u003cem\u003ehttp request\u003c\/em\u003e, and \u003cem\u003ecode\u003c\/em\u003e.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eAPI integration:\u003c\/strong\u003e uses the \u003cstrong\u003ePolyOrderbooks API\u003c\/strong\u003e with \u003cstrong\u003ePLOYORDERBOOKS_API_KEY\u003c\/strong\u003e set as an environment variable named \u003cstrong\u003ePOLYORDERBOOKS_API_KEY\u003c\/strong\u003e.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eKey requirement:\u003c\/strong\u003e the market slug you enter must match a valid PolyOrderbooks\/Polymarket market slug (as shown in the PolyOrderbooks market URL).\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eRun the workflow, submit your market slug and buy size, and get a slippage profile grounded in near-close order book reality.\u003c\/p\u003e","brand":"N8N Commerce","offers":[{"title":"Default Title","offer_id":45899965890739,"sku":"N8N-18692","price":26.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0749\/6279\/6723\/files\/6FE0yqQm8MVYgJg7HqKA3_lphNOn7W.png?v=1787735817","url":"https:\/\/buyflowscripts.com\/products\/measure-polymarket-slippage-with-n8n-form-polyorderbooks-api","provider":"N8N Commerce","version":"1.0","type":"link"}