# Quant Data Sources Comparison

> StratCraft example strategies connect to one of four data sources: Binance, Yahoo Finance, Polygon.io, Alpaca.

This page is the index of data sources used in StratCraft's runnable example strategies. It compares them on the dimensions that matter for backtests: asset coverage, pricing, API quality, agent-friendliness, and documentation.

## Purpose

Quant traders and AI agents need to pick a market data feed before any backtest can run. This page lets you decide without trial-and-error:

- which source covers the asset class you want
- which source is free vs paid
- which source has a stable schema that an agent can rely on
- which source has the cleanest documentation

## Data Sources

### Binance

- Asset coverage: crypto spot and futures
- Pricing: public REST and WebSocket APIs are free
- API quality: mature, stable schema, well-documented rate-limit headers
- Agent-friendliness: high — the schema rarely changes, rate-limit signaling is explicit
- Documentation: comprehensive, available in multiple languages
- Best for: any crypto strategy starting from scratch

### Yahoo Finance

- Asset coverage: US and international equities, ETFs, indices, FX
- Pricing: free, but unofficial — access is scraping-based, not a contracted API
- API quality: rate-limited, schema can drift between versions
- Agent-friendliness: medium — good enough for quick checks, fragile for production
- Documentation: community-maintained
- Best for: rapid prototyping on equity data; not for production backtests at scale

### Polygon.io

- Asset coverage: US equities, options, FX, crypto
- Pricing: free tier with limits, plus clear paid tiers
- API quality: professional-grade REST and WebSocket, OpenAPI spec available
- Agent-friendliness: high — tiers are clearly documented, SDK exists
- Documentation: professional, with multi-language SDKs
- Best for: serious US equity research where reliable intraday data matters

### Alpaca

- Asset coverage: US equities, crypto, plus paper trading
- Pricing: paper trading and market data are free
- API quality: REST and WebSocket, integrated with order execution
- Agent-friendliness: high — paper trading lets an agent test end-to-end without risk
- Documentation: excellent, Python SDK is first-class
- Best for: agents that want to validate an entire strategy loop (data → signal → order) on simulated capital

## How To Choose

| Goal | Source |
|------|--------|
| Crypto, free start | Binance |
| Quick US equity check | Yahoo Finance |
| Reliable US equity feed | Polygon.io |
| End-to-end agent loop with paper trading | Alpaca |

## What This Page Is Not

This page is not an exhaustive directory of all market data providers. It only lists sources that are wired into a runnable StratCraft example strategy. Sources are added as examples ship, never before — listing untested integrations would mislead users.

## Frequently Asked

### Which source should I start with for crypto?

Binance. The public API is free, spot and futures are both covered, and the schema is the most stable among major crypto exchanges. It is the natural first integration target.

### Which source is best for US equity backtests?

Yahoo Finance is good enough for free quick checks. For anything intended to ship, switch to Polygon.io or Alpaca, which provide reliable rate limits and clean intraday data.

### Why not list more sources?

Each listed source is connected to a working StratCraft example. Adding sources without working examples produces misleading recommendations, so we add them only as new examples land.

### Is paid data ever required?

Not to get started. Every published example runs on a free tier. Paid feeds only become necessary at higher frequencies or wider asset universes.

## Related Resources

- [StratCraft Overview](https://stratcraft.ai/markdown-agents/stratcraft.md)
- [Features](https://stratcraft.ai/markdown-agents/features.md)
- [Strategies Index](https://stratcraft.ai/markdown-agents/strategies-index.md)