Add Tradier API (#865)

README.md

@@ -322,6 +322,7 @@ API | Description | Auth | HTTPS | CORS |
 | [Plaid](https://plaid.com/) | Connect with users’ bank accounts and access transaction data | `apiKey` | Yes | Unknown |
 | [Razorpay IFSC](https://ifsc.razorpay.com/) | Indian Financial Systems Code (Bank Branch Codes) | No | Yes | Unknown |
 | [RoutingNumbers.info](https://www.routingnumbers.info/api/index.html) | ACH/NACHA Bank Routing Numbers | No | Yes | Unknown |
+| [Tradier](https://developer.tradier.com) | US equity/option market data (delayed, intraday, historical) | `OAuth` | Yes | Yes |
 | [VAT Rates](https://jsonvat.com/) | A collection of all VAT rates for EU countries | No | Yes | Unknown |
 
 ### Food & Drink