Stock Market APIs

Gathering financial data is rather difficult at a reasonable prize. To offer live portfolio tracking I need this data. Here is an overview of available APIs I could gather:

• Polygon
  • Solid 29$/month tier: 15-minute delayed data, unlimited API calls, 5 years historical data, fundamental data
  • First party clients available for: Python, Go, Javascript, PHP, Kotlin
  • Third party C# client: Github
  • Good documentation
• financialmodelingprep
  • Reasonable pricing starting at 19$/month, 300 requests/min, 30 year historical data (10.50$/month yearly billing)
  • Huge array of fundamental data/economic data available, (earnings calendar, IPO calendar, stock news, etc)
  • 250 requests/day for free, should be enough for testing
  • Third party C# library available Github - quality seems great
  • Good documentation
• Marketstack
  • Usable tier starting at 9.99$ with 10 000 requests/month (fundamentals included)
  • Third party(?) C# library available: Github
  • Company behind this data seems to act questionable to say the least, not an option for this reason already
  • Good documentation
• Stockdata.org
  • 9$ tier with 2500 requests/daily (~100/hour), 19$ tier with 10 000 requests/daily (~400/hour), some particular limitations
  • Fundamental data available
  • Good documentation
• Alpaca
  • Only offers price data, no stock splits, dividends, etc. (200 API calls per minute free)
  • 99$/month for al US exchange data + unlimited websockets
• Alpha Vantage
  • Free tier only includes 500 API calls a day, payed tiers start at 50$ a month => better options available
• EODHD APIs
  • Data packet that includes fundamentals starts at 79.99€/month
• Tiingo:
  • Only offers price data, fundamental data is in beta and costs extra (50 API calls per hour free)
• Category "Way to expensive":
  • Finnhub
  • Intrinio

Secondary APIs

There are some free APIs that can be used to gather secondary data:

• EconDB: Consumer Price index, Unemployment, Consumer Confidence, etc.
• FiscalData.Treasury.gov: Wide array of US fiscal data

Decision

financialmodelingprep seems to offer the most complete dataset at the best price, so I will start testing that.