Massive vs yfinance
Compare a contracted market-data platform with REST, WebSocket, and bulk flat files against a free open-source Python library for market-data work.
Integration shape
Massive (formerly Polygon.io) is a hosted market-data platform: versioned REST paths on api.massive.com with a Bearer apiKey query parameter, WebSocket streams, and S3-compatible bulk flat files. The free Stocks Basic plan lists 5 API calls per minute with two years of historical data; paid asset-class plans extend coverage. yfinance is a Python package with no key and no contract: yf.download returns DataFrames, upstream throttling is informal, and there is no SLA.
| Decision axis | Massive | yfinance |
|---|---|---|
| Shape | Hosted API (REST + WebSocket + flat files) | Python library |
| Auth | Bearer |
None |
| Free allowance | Stocks Basic: 5 calls/min, two years of history | Free software; upstream behavior can change without notice |
| Pricing | Free and paid asset-class plans; business licensing separate | Free Apache-2.0; Yahoo data rights are separate |
| Real-time | Entitlement-dependent feeds | Unofficial interfaces only |
| Bulk history | S3-compatible flat files | None |
| Accountability | Vendor contract and support | None; not affiliated with or vetted by Yahoo |
Where Massive wins
A contracted feed with documented entitlements: U.S. equity aggregates and reference data, options, futures, indices, forex, crypto, and economic datasets from one vendor, plus WebSocket streams and bulk flat files for teams that ingest at scale. When the feed breaks, there is someone to call — and the free tier’s two-year history is generous for evaluation.
Where yfinance wins
Zero friction. No key, no signup, no plan picker: a notebook goes from nothing to ticker history, financials, and options chains in minutes. For research, education, and personal analysis, the ergonomics are unmatched.
Free tiers are not production licenses
Massive’s individual pricing is not a commercial redistribution license — compare plans on asset class, historical depth, feed latency, and usage rights before building on them. yfinance’s documentation frames Yahoo data as personal and research use. Decide the data rights before designing the ingestion layer, not after the product depends on it.