yfinance

yfinance is a Python library that gives anyone free and simple access to market data from Yahoo Finance: historical prices, dividends and splits, company fundamentals, options chains, news and more, returned as pandas DataFrames. I started it in May 2017 (first published as fix-yahoo-finance) after Yahoo shut down its official API, and it has become the default way many people get market data into Python.

As of October 2026: about 25,500 GitHub stars, 3,400 forks, 187 contributors, 150 releases on PyPI, and about 18.6 million PyPI downloads in the last month. deps.dev lists about 900 PyPI packages that depend on it.

yfinance relies on Yahoo endpoints that are unofficial and undocumented, so it breaks whenever Yahoo changes something, usually without notice, and a large number of downstream tools break with it. Keeping it working is constant, reactive work.

What the funding pays for (plan: yfinance-maintenance, USD 100,000 per year):
- Regular paid maintainer time to work through the backlog (57 open issues and 52 open pull requests today) and keep response times short.
- Breakage resilience: scheduled smoke tests against the live Yahoo endpoints, alerts when responses change, faster hotfix releases, and sturdier handling of rate limits, cookies and schema changes.
- Security and supply chain: PyPI trusted publishing, build provenance and signed releases, dependency scanning, and a published security policy.
- Tests and CI across supported Python and pandas versions, using recorded fixtures so the core suite does not depend on the network.
- Documentation: an up-to-date API reference, guides, and clear migration notes for breaking changes.
- A predictable release cadence with changelogs.