Every time I built a trading UI, I hit the same wall - real data feeds cost thousands per month. Free APIs have strict rate limits. And I just wanted to test my UI. So I built trade-data-generator , an npm library that generates realistic synthetic market data for equity, forex, and crypto. The Problem Building a trading UI requires live market data. Your options are: Bloomberg/Refinitiv — $2,000+/month Free APIs — rate limited, unreliable Hardcoded fake data — not realistic, The charts look broken None of these works well for development and testing. The Solution npm install trade-data-generator Enter fullscreen mode Exit fullscreen mode Zero dependencies. Zero API keys. Works offline. How It Works const { MarketFeed } = require ( ' trade-data-generator ' ) const feed = new MarketFeed ({ type : ' crypto ' , pairs : [ { symbol : ' BTC/USDT ' , startPrice : 45000 , volatility : 0.004 }, { symbol : ' ETH/USDT ' , startPrice : 2800 , volatility : 0.005 }, ] }) feed . on ( ' tick ' , ( data ) => console .…