Alright, let’s get real for a second. When I first started algo trading, I was on a tight budget. I needed good data, but I didn’t want to spend hundreds (or thousands) of dollars on expensive APIs. Sound familiar?

The good news is, there are plenty of free or affordable market data APIs out there that won’t break the bank. The bad news? Not all of them are worth your time. So, I’ve done the legwork for you and put together a list of 10 genuinely free or low-cost API for Algo Traders that I’ve personally used or tested. Let’s dive in.

1. Alpha Vantage

Let’s start with a classic. Alpha Vantage is my go-to for stock and forex data. It’s free, easy to use, and offers both historical and real-time data. The documentation is clear, and I’ve never had trouble integrating it into my projects. If you’re new to algo trading, this is a great place to start.

 2. Mobula API

Mobula is a fantastic alternative for crypto traders. It offers real-time market data, historical prices, and even wallet tracking for over 15,000 cryptocurrencies. The free tier is generous, with 300,000 credits per month and no rate limits. I’ve used it for building crypto bots, and it’s been a game-changer.

3. CoinMarketCap API

If you’re into crypto, CoinMarketCap is a solid alternative. It offers real-time and historical data on thousands of cryptocurrencies, including prices, market capitalization, and trading volume. The free tier is limited, but it’s perfect for developers and traders who need comprehensive market data without paying a premium.

4. Yahoo Finance

Okay, I know what you’re thinking: “Yahoo Finance? Really?” But hear me out. It’s free, it’s reliable, and it covers a ton of assets—stocks, ETFs, forex, you name it. I’ve used it for quick data pulls when I didn’t need anything fancy. It’s not perfect, but it gets the job done.

5. Tiingo

Tiingo is one of those hidden gems I stumbled on a while back. It’s got a mix of stock, forex, and crypto data, and I love that it includes news sentiment analysis. The free tier is a bit limited, but it’s worth checking out if you want something a little more advanced.

6. IEX Cloud

IEX Cloud is my top pick for US stock data. It’s fast, reliable, and the free tier is surprisingly generous. Plus, it’s backed by IEX, the exchange that made waves with Flash Boys. If you’re trading US equities, this is a no-brainer.

7. Quandl (Nasdaq Data Link)

Quandl is like a treasure chest of financial data. It’s got everything from stock prices to economic indicators. Some datasets are paid, but there’s still plenty of free data to play with. I’ve used it for niche projects, and it’s always delivered.

8. Polygon (formerly Polygon.io)

Polygon is a beast when it comes to stock and options data. The free tier is limited, but if you’re serious about real-time data, it’s worth a look. I’ve used it for building high-frequency trading models, and it’s been rock-solid.

9. Financial Modeling Prep

If you’re into fundamental analysis like I am, Financial Modeling Prep is a game-changer. It offers free access to financial statements, analyst estimates, and more. I’ve used it for building valuation models, and it’s been incredibly useful.

10. OpenBB (formerly Gamestonk Terminal)

Last but not least, OpenBB is an open-source platform that aggregates data from multiple sources. It’s not a traditional API, but I love how flexible it is. I’ve used it for experimenting with different datasets, and it’s been a huge time-saver.

The Catch with Free APIs

Now, let’s be real: free APIs aren’t perfect. I’ve run into rate limits, data delays, and missing features more times than I can count. But here’s the thing—they’re a fantastic starting point. They let you test your ideas, refine your strategy, and learn the ropes without spending a dime.

And when you’re ready to scale up, you can always upgrade to a paid plan. But for now, these free tools are more than enough to get you started.

What’s Next?

If you are serious about algo trading, you know that staying ahead of the curve is everything.

Once you have your data sorted, it is time to build smarter, faster, and more efficient algorithms. Want to take your trading to the next level? Have a look at my blog on 10 AI Agent Tools That Are Reshaping the Algorithmic Trading Industry in 2025. It’s filled with all insights on how AI is revolutionizing trading—trust me, you won’t want to miss it.