HailStorm is described as 'Simple Integration and Load Testing Tool using Java 11'. There are more than 25 alternatives to HailStorm for a variety of platforms, including Windows, Linux, Mac, Online / Web-based and Self-Hosted solutions. The best alternative is soapUI, which is both free and Open Source. Other great apps like HailStorm are Apache JMeter (Free, Open Source), Katalon Studio (Freemium), locust (Free, Open Source) and hey (Free, Open Source).
Apache JMeter is an open source Java application, designed to load test functional behavior and measure performance. Originally designed for testing Web Applications, it has since expanded to other test functions as well.
Katalon Studio is a free and robust automation solution for API, Web and Mobile testing. It eliminates the complexities of building an automation framework by integrating all necessary test components with built-in keywords and project templates.
Tsung (formerly IDX-Tsunami) is a distributed load testing tool. It is protocol-independent and can currently be used to stress HTTP, WebDAV, SOAP, PostgreSQL, MySQL, LDAP and Jabber/XMPP servers. It is distributed under the GNU General Public License version 2.