Yes. You can change your mind anytime up until a fundraise closes (or 4 days after you invest, if later) and you will receive a full refund, including any fees. Unfortunately, investments cannot be cancelled after that time.
You'll receive a five-day notice via e-mail when a fundraise is about to close. Additionally, we put a 7 day warning on the fundraise page to let investors know that it will be closing soon. You can cancel at any point up until the fundraise closes (or 4 days after you invest, if later).
Once the minimum funding target is met, many companies do a "rolling close", where investments that have successfully applied to invest are executed and funds are transferred, but the round is still open to receive new investments. You'll still receive a five-day notice if this occurs. Once your funds are transferred to the company, you no longer can cancel your investment or obtain a refund.