I encountered the issue of high costs associated with paid data sources, while the free alternatives seem unreliable. I am trying to analyze the daily stocks OHLC price series. I have used the following free data sources: Yahoo Finance alphavantage.co. They both work well but look unreliable. I am concerned that they will stop giving away data for free at any moment. I have also tried the Interactive Brokers API. It caused too many problems. Please suggest some other free or inexpensive data sources (providers). I need to load about 5,000-10,000 up-to-date stocks daily OHLC price series every working day. The cost of options data appears overly high for individual traders. Can you provide some advice on this matter?
Yahoo Finance has been providing daily candles for years at not cost, I don't think they will stop offering the service. That is a safe data source if you want to trust them. Anyway, since you are looking for daily snapshots only, look for the key word "end-of-day" data. They are normally free datasets. Data providers normally charge for smaller time frames, daily data is often free. I am also a developer, so give me a shout if you need anything.
I would suggest Norgate Data for cheap and very good (Reuters) EOD data on stocks. If Metastock format is not a problem they are very good (Reuters source) and very cheap too. You can get EOD data from Metastock for very low price. Yahoo Finance was Reuters data, now it is CSI data, which you also can get them as paid version with some advantages here. So if you want exact the same (at least) as Yahoo then have a look at csidata.com. Otherwise you can also have a look at various data providers from this source: https://quantpedia.com/links-tools/?category=historical-data
If you install Ninjatrader (which is for free), you can use their charting program for free, and download historical data (end of day) from a huge amount of stocks for free. You can program NT8 in c#, but also in Python I think. And you don't have to be afraid that it may disappear soon. You also have realtime data for BTC. For free. https://ninjatrader.com/ https://kinetick.com/
Please wich problems did you experienc with ibkr? I am building my system on daily hourly based on their data
I've been using this for a few years as the API drops prices straight into a spreadsheet: https://eodhistoricaldata.com
The few symbols I don't get thru TradeStation I've taken advantage of yahoo's daily data, since at least the late 1990's. At some point I stopped worrying about it going away. IMO for this to end Yahoo would have to end. Sure that's a possibility but not likely. They've been bought and sold a couple of times and free data continues to be made available. Clicks and ad views pay for it like so much of web traffic. CSI is a good one that was mentioned. You should check with TradeStation. I don't trade stocks but they have promo's with hitting very low monthly trading volume offering platform and date free, other than very minor exchange fees of like $5-$25 a month (depending which exchanges you want) or if you want level II data, etc plus pretty low commission costs.