Designing a Financial App? Here’s How to Choose a Stock API


If you’re designing a financial app, or any kind of app that relies on data from the stock market, you’ll need some kind of stock API as an intermediary data connector. A stock API, in case you aren’t familiar, serves as a kind of intermediary between your app and the stock market itself. It draws data on stocks in real-time, allowing your users to track price fluctuations as they unfold, and gather the data they need to make important financial decisions.

These days, there are many different stock APIs to choose from, some of which are paid, and some of which are free. So what factors should you consider when choosing a stock API?

Adjusted vs. Unadjusted Historical Prices

First, you should consider whether this stock API uses adjusted or unadjusted historical prices. Occasionally, companies will trigger or be subject to events that result in a change in price that doesn’t necessarily reflect the company’s performance. The most prominent example here is a stock split; when a company is growing rapidly, they may choose to issue a stock split, doubling the shares of all shareholders and cutting the price per share in half. While the held value of each investor doesn’t change, the price appears to plummet overnight.

Stock APIs that adjust prices attempt to stabilize and account for these unexpected changes; those that are unadjusted may provide users with a false impression.

Exchange Specificity vs. Aggregation

Another point to consider is whether your stock API is focused on data from a specific exchange, or whether it aggregates data from multiple different exchanges. There are advantages and disadvantages to each, so your choice is ultimately going to depend on how you want your app to function. If you want to trade or make decisions based only on one specific exchange, an exchange-centric stock API is favorable; otherwise, you’ll want one with aggregated data.

Available Data

For the most part, you’ll want a stock API that gathers as much data as possible, though some niche apps may be fine with restricted access. The big considering factor here is whether to draw only current, real-time stock prices, or whether to access historical prices as well.

Currency Selections

Some stock APIs are finicky or unreliable when it comes to translating information from different exchanges. You’ll want to evaluate this in your stock API of choice; for example, does this API automatically list all information in USD, or does it rely on the currency for a specific exchange?

Scraping Sources

You’ll also want to investigate where this stock API is getting its data from. If it’s only scraping public sources, this could be a red flag; these data tend to be unreliable and could be delayed, inaccurate, or both. Make sure you’re getting information from reliable sources.

Language Availability

Different stock APIs may offer APIs in different languages. If you’re the one doing the programming, or if you have a key developer working on the app, you’ll want to choose a stock API that caters to your programming language of choice. If you’re still in the early stages and you’re not sure what you want, consider choosing an API that supports many different languages.


When examining a stock API, ask yourself how much support it’s getting regularly. Is this stock API made by a specific company, with a dedicated team of developers? If so, do they regularly push new updates to the code? Do they listen to developer concerns and address them when possible? If this is an open source API, is there substantial community support for it? Are there forums where you can ask questions and get assistance if you need it?

Reviews and Experiences

It’s also a good idea to see how other people have used and enjoyed this stock API in the past. Are there reviews or testimonials about this stock API? What about the other APIs you’re considering? Is there a persistent issue that people seem to experience with it, or does everyone seem to get what they need out of it?


Finally, consider the cost. Some stock APIs are packaged and sold as products; you may need to pay a flat rate to use them indefinitely, or you may be required to pay a subscription. Others are entirely free. Obviously, free choices sound like the better option—but make sure they have everything you need before committing your decision.

Your stock API has the power to influence the functionality, reliability, consistency, and security of your financial app, so it’s not a decision to take lightly. Review the top stock APIs available, consider your priorities carefully, and make whatever choice seems to fit your app’s unique needs the best.