Write ladder logic in a browser tab. Watch a simulated machine execute your program in real time. No download, no licence key, no credit card.
You’re watching a real PLC simulator run right now. No install, no sign-in. The scan counter increments every 16 ms, exactly as a physical controller would. Open this scenario in the full editor →
If you have searched for a free PLC simulator before, you already know the drill. You find a product name, follow the link, and discover that "free" means a 30-day trial, a student licence that expires with your enrollment, or a stripped demo that will not let you save. The genuinely free tools either require a full desktop install or give you a blank canvas with no guidance on what to program.
Siemens PLCSIM ships inside TIA Portal. A Professional licence costs upwards of $1,500 USD. Rockwell’s Studio 5000 Logix Emulate is a commercial product aimed at system integrators, not learners. LogixPro is a Windows-only teaching tool sold on a per-seat basis. CoDeSys offers a free IDE with a simulator, but you are on your own to build a plant model to test against — there are no scenarios, no objectives, no test harness.
The pattern is consistent: every product that runs against a real machine model either costs money or locks you into one vendor’s toolchain. For a student who wants to practice motor-start-stop logic before a job interview, or a plant engineer who wants to check a rung change before a commissioning window, that barrier is unnecessary. This PLC simulator removes it.
No trial clock. No watermarks. No locked exports. Here is exactly what is available without paying anything.
2 scenarios load instantly with no account: Traffic Light and Motor Start/Stop. Create a free account (no credit card) to unlock 2 more. All 4 run the full editor with real auto-graded test cases.
The same Monaco-based editor used on paid tiers. Contacts, coils, timers, counters, edge detection, compare, math, and PID function blocks — all wired up and available on the free plan.
Switch between IEC 61131-3, RSLogix-style AB, and TIA Portal-style Siemens syntax from the toolbar. Dialect choice is not a paid feature.
Every free scenario ships with a scripted test suite that evaluates sequencing, interlocks, and timing. You get pass/fail feedback with failure reasons — not just a green tick.
Windows, Mac, Linux, Chromebook. Any modern Chrome, Firefox, Safari, or Edge release. No admin rights required. This matters in locked-down university labs and corporate environments.
There is no trial clock counting down. The free tier stays free. You can come back six months later and your two anonymous scenarios are still there. Upgrade when you need the full 40-scenario library.
Being straight about this: the free plan gives you 4 scenarios out of 40. Here is what a paid plan adds.
These are legitimate tools. Each is right for a specific use case. The table shows what each one actually gives you for free.
| Tool | Free price | Browser-based | Auto-graded | Scenarios included | Multi-dialect |
|---|---|---|---|---|---|
| This simulator (free tier) | Free | Yes | Yes | 4 | IEC, AB, Siemens |
| OpenPLC Runtime | Free (open-source) | No — desktop install | No | None (bring your own) | IEC 61131-3 only |
| PLC-Fiddle | Free | Yes | No | None (blank canvas) | Ladder only |
| LogixPro LITE | Commercial licence | No — Windows only | Limited | Small set (AB-only) | AB only |
| CoDeSys (free edition) | Free IDE + simulator | No — desktop install | No | None (bring your own) | IEC 61131-3 only |
| Siemens PLCSIM | Bundled with TIA Portal (~$1,500+) | No — Windows only | No | None (bring your own) | Siemens only |
Pricing sourced from each vendor’s public pages. Correct as at April 2026 — verify before purchase.
The Traffic Light scenario is the fastest way to see a free PLC simulator in action. It loads immediately at /scenarios/traffic-light with no account, no form, no confirmation email. Open the URL and the editor is live.
The scenario asks you to implement a four-way traffic-light sequence: red, all-red safety phase, green, amber, then back to all-red. Auto-graded test cases check that your timing windows hit within the tolerance bands, that the all-red phase fires before green, and that the sequence loops indefinitely. If you pass every test, you see it in the test panel immediately.
This is also the scenario that shows new users what separates a PLC programming simulator with auto-grading from a blank-canvas editor. You know exactly whether your logic is correct, and you know why it failed if it did not pass.
No install. No credit card. No trial clock. The Traffic Light scenario loads instantly without an account — or register for free to unlock two more.
Related: PLC simulator · PLC programming simulator · all scenarios · pricing