Top Free & Open Source PLC Programming and Simulation Tools

Programmable Logic Controller (PLC) programming remains dominated by vendor-specific tools, but many engineers, system integrators, and manufacturers actively search for free and open source PLC programming and simulation tools. These tools are commonly used for learning, prototyping, soft-PLC deployments, offline testing, and automation research.

What qualifies as a PLC programming and simulation tool

For inclusion, a tool must support at least one of the following: PLC-style programming languages, a runtime or simulator, or a workflow commonly used in industrial automation. Pure electronics simulators or vendor-locked trial software is excluded.

Top Free & Open Source PLC Programming and Simulation Tools

OpenPLC Editor

OpenPLC Editor is a free and open-source IEC 61131-3 programming environment. It supports Ladder Diagram (LD), Function Block Diagram (FBD), Structured Text (ST), Instruction List (IL), and Sequential Function Chart (SFC).

It is designed to work directly with the OpenPLC Runtime, making it one of the most complete open PLC development stacks available today.

OpenPLC Runtime

OpenPLC Runtime is a software PLC that executes programs created in OpenPLC Editor. It runs on Windows, Linux, and embedded platforms, making it suitable for soft-PLC testing, education, and industrial prototyping.

Beremiz

Beremiz is a mature open-source IEC 61131-3 environment combining an IDE, compiler, and runtime integration. It supports classic PLC workflows and industrial communication protocols.

Beremiz is often used in research labs, custom automation projects, and advanced training environments.

MATIEC

MATIEC is an open-source IEC 61131-3 compiler. It converts PLC languages into C code and is frequently used as a backend for custom PLC toolchains, CI pipelines, and automated testing frameworks.

While it is not an IDE, it is a foundational component in many open PLC stacks.

Eclipse 4diac IDE

Eclipse 4diac is the reference open-source IDE for IEC 61499, which focuses on distributed, event-driven automation systems. It is widely used in modern automation research and multi-device control scenarios.

4diac FORTE Runtime

FORTE is the runtime environment for executing IEC 61499 applications created in the 4diac IDE. It enables real deployment and testing of distributed PLC logic across industrial devices and edge systems.

LDmicro

LDmicro is a lightweight ladder logic editor with built-in simulation. It is popular for learning ladder logic and for embedded-style automation projects.

Although not a full industrial PLC IDE, it is extremely fast for testing basic control logic.

ClassicLadder

ClassicLadder is an open-source ladder and Grafcet (SFC-style) programming tool with simulation capabilities. It is often used for training, Modbus-based experiments, and soft-PLC testing.

CODESYS Development System

CODESYS provides a free PLC programming IDE supporting IEC 61131-3 languages. While proprietary, the IDE itself is free and commonly used for learning and offline simulation in demo mode.

PLC Simulator Online

PLC Simulator Online is a browser-based ladder logic simulator. It is useful for quick demonstrations, basic training, and zero-install testing. It is not open source but remains a popular free learning tool.

Comparison overview

Open-source PLC tools typically fall into three categories: full IEC 61131-3 stacks, distributed automation platforms (IEC 61499), and lightweight ladder simulators. Choosing the right tool depends on whether the goal is learning, industrial prototyping, or system-level automation design.

How PLC simulation tools are used in practice

In real engineering workflows, free PLC tools are rarely used alone. Engineers typically combine a programming IDE with a soft-PLC runtime to test logic before deploying it to vendor hardware. Simulation is used to validate sequences, interlocks, alarms, and safety logic before commissioning.

Final takeaway

Free and open-source PLC programming and simulation tools are fully capable of supporting real automation workflows in 2025. They are widely used for education, research, offline testing, and even production soft-PLC deployments.

The main limitation is not software capability, but integration effort and familiarity. Engineers who invest time in these tools gain flexibility, transparency, and control over their automation logic without being locked into a single vendor ecosystem.

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