# API Research Log

| Date | Provider | Source | Findings used in architecture | Test status |
| --- | --- | --- | --- | --- |
| 2026-10-20 | Alpaca | [Authentication](https://docs.alpaca.markets/us/v1.1/docs/authentication-1) | Trading API uses key-based authentication; paper trading has distinct credentials and the documented `paper-api` domain. | Not tested; no credentials used. |
| 2026-10-20 | Alpaca | [Market Data](https://docs.alpaca.markets/us/docs/about-market-data-api) | HTTP/WebSocket access is documented. Plans differ in real-time coverage, history access and request limits; documentation lists Basic and Algo Trader Plus plan characteristics. | Not tested. |
| 2026-10-20 | Alpaca | [Paper Trading](https://docs.alpaca.markets/us/v1.4.2/docs/paper-trading) | Paper fills use simulation and omit market impact, information leakage, latency slippage, queue position, price improvement, regulatory fees, and dividends. | Not tested. |
| 2026-10-20 | Polygon.io | [Stocks API overview](https://polygon.io/docs/rest/stocks/overview?auth=signup) | US stocks documentation covers REST, WebSocket and flat files; timestamps are UTC Unix timestamps. | Not tested; no credentials used. |
| 2026-10-20 | Interactive Brokers | [TWS API introduction](https://interactivebrokers.github.io/tws-api/introduction.html) | API needs a running TWS or IB Gateway; paper trading is available but has limitations; client message rate limit is documented. | Not tested; no account or gateway used. |
| 2026-10-20 | Interactive Brokers | [Initial setup](https://interactivebrokers.github.io/tws-api/initial_setup.html) | Gateway/session authentication and market-data subscriptions require operational design; the documentation warns about paper/live session distinctions. | Not tested. |

This log must be extended with current official URLs, contract details, tested API/SDK versions, permission evidence, and observed behavior immediately before provider code is written.