Support

How long is the free trial?

60-day free Pro trial with all Pro features unlocked. No credit card required. After 60 days, core features remain free forever.

Installer vs Portable version?

Installer creates Start Menu shortcuts. Portable is a single executable that runs without installation.

Why do I need wc3270/x3270?

IM3270 uses the x3270 suite for core 3270 emulation while providing a modern UI.

Can I use SSL/TLS?

Yes! Check "SSL" in the connection dialog or use --ssl command line flag.

How do I customize shortcuts?

Open the Keyboard Shortcuts Editor via Edit → Keyboard Shortcuts or Ctrl+Shift+K.

Where are settings stored?

Windows: %APPDATA%\im3270
Linux: ~/.config/im3270

Where can I find diagnostic information?

Check ~/.im3270/im3270.log for startup diagnostics. This log contains detailed information about s3270 detection, connection attempts, and error details that can help troubleshoot issues.

How do I verify my download is authentic?

Starting with v0.44.0, all releases include SHA256 checksums and GPG signatures. After downloading, verify with:

• Quick check: sha256sum -c SHA256SUMS --ignore-missing
• Full GPG verification: See our Security page for step-by-step instructions

The Linux installer also automatically verifies the AppImage checksum during installation.

Why would I use IM3270 when IBM offers TNZ and ZTI for free?

TNZ and ZTI are good options for occasional browser-based access, and if they cover your needs we genuinely recommend using them.

IM3270 is built for developers and sysadmins doing heavy daily mainframe work on Linux who need a native app experience:

• Keyboard shortcuts work correctly – browser-based tools conflict with browser shortcuts (F5 refreshes the page instead of sending PF5)
• IND$FILE file transfer, macro recording, and split screen sessions are not available in browser-based emulators
• TNZ/ZTI require specific z/OS PTFs and network configuration – not always available in every shop, or on Hercules/TK5 environments
• A native app with proper tab management and keyboard handling makes a measurable difference across an 8-hour workday

If you work occasionally on mainframe, TNZ/ZTI are a solid free choice. If you live in the terminal all day on Linux, IM3270 is built for you.

Everyone is talking about AI and code generators – why do I still need a terminal emulator?

AI tools are transforming how code is written. But the mainframe still needs to run it.

Every COBOL program that gets generated, every JCL job that gets submitted, every dataset that gets queried – it all executes on z/OS. Someone still has to connect to that system, deploy the code, check the output, respond to abends, and manage the environment. That person needs a terminal.

In fact, AI is making terminal emulators more relevant, not less:

• Developers who never touched mainframe before are now generating COBOL and JCL with AI assistants and need a way to run it
• AI tools produce code faster, which means more deployments, more job submissions, more debugging sessions
• The mainframe processes $10 trillion in transactions daily – no AI generator replaces the need to connect to it

Think of it this way: AI writes the code, IM3270 is how you talk to the machine that runs it.

Don't browser-based emulators like TNZ or ZTI also require a server installed?

Yes – browser-based emulators require server-side infrastructure on the mainframe side (z/OSMF, Host On-Demand, or equivalent), plus the right PTFs and network configuration. In many shops – especially older installations or Hercules home labs – that infrastructure isn't available.

IM3270 connects directly over the standard TN3270 port that every z/OS installation already exposes. No server-side setup required beyond what's already there.