CDS isn't an OTC instruments. Swaps are now traded on SEFs like MarketAxess or TradeWeb. Just because you don't have access to the data don't think that professionals don't. But this isn't OHLC data for listed equities. Expect to pay. Actually high quality realtime equity data (ITCH,PITCH,OpenBook Ultra,etc...) costs real money as well.

Checkout CDS and FI market data offerings: https://www.marketaxess.com/data/marketdata.php

But your idea is correct. CDS Spreads can be predictive of dramatic shocks in an equities price.

That is awesome

Yeah i get the promise: professionals do this, pay a premium for that

Until they don't because someone provides the data for free or next to nothing

In this town we call it disruption

Who's going to provide that data for free when they can charge a LOT of money for access to it. Ever notice why free data on Google or Yahoo are 15 min delayed?

I know what the exchanges charge for data access, and even if you pay it is in an antiquated format.

Tradier has been providing equity and option tick data for free for years in a clean RESTful API with the capability of websockets and streaming. So thats the answer to your question of who.

Like I said, in this town we call it disruption.

Thats part of their business model. I have not used their data but I can tell you that all tick data is not created equally.

We are unlikely to ever see CDS data for free since individuals cannot trade them as most retail investors are not Eligible Contract Participant. Some brokerages give away data to get people to trade with them so there its about customer acquisition.

I am a developer that has done a few projects on the tradier API. Agreed