PLC-LadderSeven free PLC simulators compared honestly in 2026: PLC-Ladder, PLC Fiddle, OpenPLC, CODESYS, Do-more Designer, CCW and TIA PLCSIM — which fits your need.
A free PLC simulator is the difference between reading about ladder logic and actually learning it — but "free PLC simulator" covers everything from a browser toy to a crippled trial of a ₹2-lakh engineering suite, and picking wrong wastes an evening. Here are seven genuinely usable free options in 2026, compared honestly: what each really costs (money, installs, registration), which IEC 61131-3 languages it runs, and who it actually fits. Yes, our own tool is on the list — first, because it's ours — but every entry includes the cases where a competitor is the better pick, because a comparison you can't trust is worth nothing.
The Comparison at a Glance
| Tool | Truly free? | Languages | Install | Best for |
|---|---|---|---|---|
| PLC-Ladder | Free plan, no install | Ladder, FBD, ST | None — browser | Learning all three languages; HMI testing via OPC UA |
| PLC Fiddle | Free | Ladder only | None — browser | Quick rung sketches |
| OpenPLC | Free, open source | All five IEC | Editor + runtime | Open-source projects, cheap hardware (Pi, ESP32) |
| CODESYS | Free IDE | All five IEC | Heavy, Windows | Closest free thing to a professional IDE |
| Do-more Designer | Free | Ladder (vendor dialect) | Windows | AutomationDirect users; solid built-in sim |
| Connected Components Workbench | Free | Ladder, FBD, ST | Heavy, Windows | A taste of the Rockwell world (Micro800 only) |
| TIA Portal + PLCSIM | Trial only (21–30 days) | All (Siemens dialects) | Very heavy | Siemens-specific prep, short-term |
1. PLC-Ladder
PLC-Ladder runs ladder, FBD and structured text in the browser — no install, no registration wall for the core simulator — with the three views editable as one program, a compiler that checks types, instances and duplicate coils before anything runs, and (uniquely in this list) one-click OPC UA exposure, so Ignition or UaExpert can drive your simulated logic like a real controller. Free plan limits: one exposed OPC UA session at a time. Honest gaps: no vendor-dialect emulation (it speaks IEC, not Rockwell or Siemens accents) and no 3D machine visuals. Pick it for: learning the languages, testing logic ideas fast, and HMI development without hardware. Pick something else for: practicing a specific vendor's IDE.
2. PLC Fiddle
The quick sketchpad of the category: free, browser-based, instant. Ladder only, simplified instruction set, limited I/O — closer to a whiteboard that executes than a simulator. Pick it for: trying one rung idea in 30 seconds. Outgrow it when: you need FBD, ST, timers beyond basics, or anything structured.
3. OpenPLC
The open-source standard-bearer: GPL-licensed editor plus a runtime that genuinely supports all five IEC 61131-3 languages and runs on real cheap hardware — Raspberry Pi, ESP32, old laptops. The trade: you install and assemble the pieces yourself, documentation has gaps, and the editor is less polished than commercial IDEs. Pick it for: open-source conviction, hobbyist hardware projects, Modbus experiments. Outgrow it when: you want compile-time hand-holding or zero setup.
4. CODESYS
The most professional free IDE in existence: the full development system is free, all five languages, and half the industrial world's controllers run its engine underneath. Caveats: Windows-only development, a steep learning curve, and the free soft-PLC runtime for Windows is time-limited per session (it stops after a period and needs restarting — fine for learning, not for anything permanent). Pick it for: the closest free approximation of a professional engineering workflow, and as the natural next step after browser tools. Outgrow it when: honestly, many never do.
5. Do-more Designer
AutomationDirect's free, full IDE with a competent built-in simulator — no hardware purchase required, no time limit. It speaks the Do-more instruction set (a vendor ladder dialect, not IEC-pure), which is a feature if you'll use their PLCs and a detour if you won't. Pick it for: a free, stable, installable Windows simulator with vendor-grade depth. Mind: skills transfer conceptually, not syntactically.
6. Connected Components Workbench (Rockwell)
Free from Rockwell, with ladder, FBD and ST and a simulation mode — but scoped to the Micro800 line only; it will not program or feel like ControlLogix/Studio 5000. Pick it for: a legitimate free taste of the Rockwell ecosystem (and pair it with our Allen-Bradley ladder guide for the XIC/XIO/OTE vocabulary). Don't mistake it for: Studio 5000 practice.
7. TIA Portal with PLCSIM (Siemens)
The one trial on the list, included because people ask: full Siemens engineering suite with PLCSIM, free for 21–30 days, then unusable without a license. Multi-gigabyte download, registration, Windows. Pick it for: a bounded sprint before a Siemens-specific job or exam. Pick anything else for: ongoing learning — a countdown timer is a bad study partner.
How to Choose in One Paragraph
Starting from zero → a browser tool today (ours or Fiddle), because the simulator you can open right now beats the better one you'll install someday. Learning all of IEC 61131-3 properly → PLC-Ladder for the three-views-one-logic workflow, then CODESYS when you want the professional IDE experience. Headed for a known vendor → that vendor's free tool (CCW, Do-more) alongside a neutral one, so you learn concepts once and dialects separately. Building on hobby hardware → OpenPLC, nothing else runs on a ₹500 board. And whichever you pick: build the seal-in, the three timers and a counter with edge detection in it during week one — the tool matters less than those three circuits.