Hercules

Windows · Mac · Linux

Freedom report

Three barsScore 6.5

Free tierA free tier is on its own pricing page
Open codeNo open-source code on record
Runs widely3 of 6 device platforms
DocumentedPlans, terms and facts published

Hercules is ranked #12 of 37 in emulator software on Freedom251. It runs on Linux, macOS, Windows. There is a free plan.

Hercules plans and pricing

All plans

Hercules Free Q Public Licence · source code and binary downloads hercules-390.eu · 1 Oct 2026

Compared on emulator software

Free plan: Yes
Supported targets: System/370, ESA/390, z/Architecture
Host operating systems: Linux, Windows, Solaris, FreeBSD, Mac OS X
Snapshots and restore: Yes
Debugging tools: Yes
Network simulation: Yes
Automation access: Yes

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The record

Purpose: Hercules is an open-source software implementation of the System/370, ESA/390 and 64-bit z/Architecture mainframe architectures.
Execution: It lets a PC execute programs designed to run on an IBM mainframe.
I/O emulation: Hercules emulates mainframe I/O devices using PC devices, including DASD files and local tn3270 sessions.
Operating systems: Hercules does not provide operating-system facilities, so users must supply an operating system or standalone program.
Architecture support: The emulator can run z/OS, z/VM, z/VSE, OS/390, VM/ESA, VSE/ESA and older related IBM operating systems when legally licensed.
Key features: Advanced features include dynamic reconfiguration, an integrated console, interpretive execution and z/Architecture support.
Networking: Hercules can connect guest TCP/IP networking to the host through a TUN/TAP interface and its hercifc program.
Shared devices: Shared device support allows multiple Hercules instances to share devices through client and server instances.
Security: The networking documentation warns that unrestricted access to hercifc can create a potential security exposure.
License: Hercules is OSI Certified Open Source Software licensed under the Q Public Licence.
Production suitability: The FAQ says Hercules has never claimed to be production-capable and was intended as a system programmer's toy.
Support: Paid technical support may be available through Open Source Mainframes, Inc., while free support is provided through Hercules discussion forums.
Download formats: The site offers source archives plus Windows 32-bit and 64-bit installer and binary packages.
Unimplemented features: Documented unsupported features include ESCON, FICON, PR/SM, coupling links and several z/Architecture facilities.
Price from: Free

Where it ranks on Freedom251

Best Emulator Software in 2026#12 of 37

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Sources

hercules-390.eu· checked 1 Oct 2026
hercules-390.eu/hercfaq.html· checked 1 Oct 2026
hercules-390.eu/herctcp.html· checked 1 Oct 2026
hercules-390.eu/shared.html· checked 1 Oct 2026
hercules-390.eu/hercsupp.html· checked 1 Oct 2026