Build a Price Comparison Tool in 15 Minutes with the Marketplace Price API

Ever tried to find the best price for something across multiple marketplaces? You'd need to open OfferUp, Poshmark, Reverb, TCGPlayer — each with different search interfaces and no way to compare side by side. The Marketplace Price API solves this with a single unified /search endpoint that queries multiple marketplaces simultaneously and returns normalized results. In this tutorial, we'll build a CLI price comparison tool in under 15 minutes. What We're Building A Node.js script that: Takes a search query as input Searches across 4 marketplaces in parallel Shows a sorted comparison table with the best prices Prerequisites Node.js 18+ A free RapidAPI account ( sign up here ) Step 1: Get Your API Key Subscribe to the Marketplace Price Tracker API on RapidAPI. The free tier gives you 500 requests/month — plenty for this tutorial. Copy your X-RapidAPI-Key from the API dashboard. Step 2: Set Up the Project mkdir price-compare && cd price-compare npm init -y Create a .env file: RAPIDAPI_KEY