Commercial PLC programming software (Studio 5000, TIA Portal, Unity Pro) costs thousands per license. If you're learning, prototyping, or working on a budget, here are the best free alternatives in 2026 — compared by features, vendor support, and real-world usability.
Comparison Table
| Software | Price | Languages | Vendor Export | Best For |
|---|---|---|---|---|
| Plaxio | Free | LD, FBD, SFC | Rockwell, Siemens, Schneider, PLCopen | Vendor-neutral dev, AI-assisted coding |
| OpenPLC | Free (GPL) | LD, FBD, ST, IL, SFC | None (custom runtime) | DIY projects, Raspberry Pi, Arduino |
| CODESYS | Free (limited) | All IEC 61131-3 | CODESYS-compatible PLCs only | CODESYS runtime devices |
| LDMicro | Free (GPL) | LD only | AVR, PIC, Arduino | Microcontroller ladder logic |
| Beremiz | Free (GPL) | LD, FBD, ST, IL, SFC | Modbus, EtherCAT | Open-source automation |
1. Plaxio (Recommended)
Best for: Vendor-neutral development, learning, and prototyping
What It Is
Plaxio is a modern desktop IDE for PLC programming with full IEC 61131-3 support. Write logic in Ladder Diagram, FBD, or SFC, simulate in real time, and export to Rockwell L5X, Siemens SimaticML, Schneider XEF, or PLCopen XML.
Key Features
- ✅ Visual editors for LD, FBD, SFC
- ✅ AI-assisted code generation (natural language → ladder logic)
- ✅ Live tag monitoring and simulation
- ✅ Built-in HMI/SCADA simulator
- ✅ Export to all major vendors (Rockwell, Siemens, Schneider)
- ✅ Import existing L5X/SimaticML/XEF files
- ✅ 100% offline — no cloud dependencies
Pros
- Free forever, no license restrictions
- Modern UI (dark mode, responsive)
- AI helps generate boilerplate logic
- Round-trip vendor export/import
- Active development, regular updates
Cons
- Cannot download directly to physical PLCs (vendor tools required for that step)
- No Structured Text (ST) support yet (roadmap item)
- Newer project, smaller community than OpenPLC
2. OpenPLC Editor
Best for: DIY automation, Raspberry Pi, open-source projects
What It Is
OpenPLC is an open-source PLC runtime + editor that runs on Linux, Windows, and embedded devices. It uses MatIEC compiler and supports all 5 IEC 61131-3 languages.
Key Features
- ✅ All 5 IEC languages (LD, FBD, ST, IL, SFC)
- ✅ Runs on Raspberry Pi, Arduino, Linux
- ✅ Modbus RTU/TCP, DNP3, EtherCAT support
- ✅ Web-based HMI (ScadaBR integration)
- ✅ Fully open-source (GPL v3)
Pros
- Free and open-source
- Active community, good documentation
- Perfect for hobby automation
- No vendor lock-in
Cons
- Cannot export to commercial PLCs (Rockwell, Siemens, etc.)
- Editor UI is dated (based on Beremiz)
- No AI features
- Runtime is not industrial-certified
3. CODESYS
Best for: CODESYS-compatible PLCs
What It Is
CODESYS is a commercial platform with a free IDE. It's the most widely used third-party PLC runtime — hundreds of PLC vendors license CODESYS for their hardware.
Key Features
- ✅ Full IEC 61131-3 compliance
- ✅ All 5 languages + CFC (Continuous Function Chart)
- ✅ Works with 500+ PLC models (Schneider, Wago, Beckhoff, etc.)
- ✅ Professional-grade debugging
Pros
- Industry-standard tool
- Extensive library of function blocks
- Direct PLC download support
- Large user community
Cons
- Only works with CODESYS-based PLCs (no Rockwell, Siemens AB, Omron)
- Free version has limitations (2-hour runtime, visualization disabled)
- Steeper learning curve
4. LDMicro
Best for: Microcontroller ladder logic (Arduino, AVR, PIC)
What It Is
LDMicro is a lightweight LD-only editor that compiles directly to microcontroller C code. Great for replacing relay panels with a $5 Arduino.
Pros
- Extremely simple — 5-minute learning curve
- Direct Arduino/AVR/PIC code generation
- Tiny binary (1MB download)
Cons
- Ladder Diagram only (no FBD, ST, SFC)
- No commercial PLC support
- Limited function blocks
5. Beremiz
Best for: Open-source automation, Linux-based systems
What It Is
Beremiz is the editor behind OpenPLC. It's a full IEC 61131-3 IDE with Modbus, CANopen, and EtherCAT support.
Pros
- All 5 IEC languages
- Open-source (GPL)
- Industrial fieldbus support
Cons
- Complex setup for beginners
- Outdated UI
- No vendor export
Which Should You Choose?
Choose Plaxio if:
- You want to learn PLC programming without committing to one vendor
- You need to export to Rockwell, Siemens, or Schneider formats
- You want AI-assisted logic generation
- You value modern UI and active development
Choose OpenPLC if:
- You're building DIY automation (home projects, hobby)
- You want to run PLC logic on Raspberry Pi or Arduino
- You need all 5 IEC languages including Structured Text
- You prefer fully open-source software
Choose CODESYS if:
- You're working with CODESYS-based PLCs (Schneider M221/M241, Wago, Beckhoff)
- You need to download directly to hardware
- You want the most advanced debugging tools
Choose LDMicro if:
- You're replacing simple relay logic with an Arduino
- You only need Ladder Diagram
- You want the simplest possible tool
Summary
- Plaxio — Best for vendor-neutral learning and prototyping with AI features
- OpenPLC — Best for DIY projects and Raspberry Pi automation
- CODESYS — Best if you have CODESYS-compatible hardware
- LDMicro — Best for simple Arduino/AVR ladder logic
- Beremiz — Best for advanced open-source automation
All of these tools are free to start. Try Plaxio first if you're learning PLC programming or need vendor export. Download now →