Looking for a smart way to earn passive income? Investing in the stock market doesn’t have to feel like betting on the roulette table.

If you want to know everything about a stock before buying a single share, use Tykr Stock Screener. This Stock education tool tracks 30,000 US and international stocks to help you determine whether an investment is worth the risk. Your first investment is this lifetime subscription, but it’s only going to be a buyer’s market for a few days more while this sale lasts.

Tykr can’t guarantee an investment is going to pay out. But what it can do is give you a summary of a stock’s recent price history, a financial strength score, and a margin of safety. If you want to find out how Tykr does the math for each stock, all calculations are totally open source. Tykr even gives you access to investment guides, webinars, and other educational resources to help you become a stock market pro.

You only have until October 15 at 11:59 PM Pacific to use code STOCK and get a Tykr lifetime subscription for an extra $20 off.