Commercial SCADA software costs thousands of dollars per license. For students, small plants, research labs, and proof-of-concept projects, that cost is a barrier.
The good news: several free and open-source SCADA platforms now deliver real-time monitoring, alarm management, HMI design, data logging, and PLC integration — without any licensing cost. Some have no tag limits. Some run in a web browser. Some support IEC 104, DNP3, and IEC 61850.
This guide reviews 12 free SCADA software platforms available in 2026. For each one, you get: what it does, which protocols it supports, what operating systems it runs on, whether it has tag limits, and where to download it.
Table of Contents
1. Quick Comparison Table
| Software | License | Tag Limit | Web Interface | OS | Key Protocols | Best For |
|---|---|---|---|---|---|---|
| Rapid SCADA | Open source (Apache 2.0) | Unlimited | Yes | Windows, Linux | Modbus, OPC UA, MQTT, SNMP | General-purpose SCADA, IIoT |
| SCADA-LTS | Open source (GPL) | Unlimited | Yes (browser-only) | Windows, Linux, macOS (Java) | Modbus TCP/RTU, DNP3, IEC 101/104, SNMP | Web-based monitoring, education |
| JSON-SCADA | Open source (GPL) | Unlimited | Yes (Grafana) | Windows, Linux | IEC 104, IEC 61850, DNP3, OPC UA, MQTT, Modbus | Power system SCADA, substations |
| OpenSCADA | Open source (GPL/LGPL) | Unlimited | Optional | Linux (primary) | Modbus, OPC, custom | Research, custom projects |
| ScadaBR | Open source (GPL) | Unlimited | Yes | Windows, Linux, macOS (Java) | Modbus TCP/RTU, OPC, SNMP | Small plants, education |
| OSHMI | Open source (GPL) | Unlimited | Yes (HTML5) | Windows, Linux | IEC 104, IEC 61850, DNP3 | Substations, control centers |
| Ignition (Trial) | Commercial (free trial) | Unlimited (2-hour reset) | Yes | Windows, Linux, macOS | Modbus, OPC UA, MQTT, Allen-Bradley, Siemens | Enterprise SCADA training |
| VTScada LIGHT | Freeware | 50 tags | Yes | Windows | Modbus, DNP3, OPC, BACnet | Small systems, demos |
| IndigoSCADA | Open source (GPL) | Unlimited | No | Windows, Linux | Modbus, IEC 104, IEC 101, DNP3, OPC | Lightweight field SCADA |
| WinTr SCADA | Freeware | 200 tags (free tier) | No | Windows | Modbus, OPC DA, Siemens S7, MQTT | HMI design, education |
| Fernhill SCADA | Freeware (limited) | 100 tags | No | Windows, Linux | OPC, ODBC | Client-server SCADA |
| SZARP | Open source (GPL) | Unlimited | Yes | Linux, Windows | Modbus, custom | Distributed monitoring, utilities |
2. Rapid SCADA
The most popular fully free SCADA platform.
Rapid SCADA is an open-source industrial automation platform with no tag limits, no license restrictions, and no expiration date. It supports real-time data acquisition, alarm management, trending, and automatic control.
| Feature | Details |
|---|---|
| License | Apache 2.0 (open source) |
| Tag limit | Unlimited |
| OS | Windows, Linux |
| Web interface | Yes (Webstation module) |
| Protocols | Modbus RTU/TCP, OPC UA, MQTT, SNMP, HTTP/JSON |
| Database | PostgreSQL, SQL Server, MySQL |
| Language | C# (.NET) |
| Download | rapidscada.org |
Best for: General-purpose SCADA, IIoT systems, energy monitoring, building automation. Excellent documentation and active community.
3. SCADA-LTS
Browser-based SCADA with strong protocol support.
SCADA-LTS is a Java-based, web-enabled open-source SCADA system. The entire interface runs in a web browser — no client installation needed. It supports real-time data updates, alarm handling, trending, and data logging.
| Feature | Details |
|---|---|
| License | GPL (open source) |
| Tag limit | Unlimited |
| OS | Windows, Linux, macOS (Java/Tomcat) |
| Web interface | Yes (browser-only — no desktop client) |
| Protocols | Modbus TCP/RTU, DNP3, IEC 60870-5-101, IEC 60870-5-104, SNMP, HTTP, SQL |
| Database | MySQL |
| Language | Java |
| Download | github.com/SCADA-LTS |
Best for: Web-based monitoring, distributed systems, classrooms, remote access. One of the few free platforms supporting IEC 104 and DNP3.
4. JSON-SCADA
The most capable free SCADA for power systems.
JSON-SCADA is a portable, MongoDB-based SCADA/IoT platform that supports IEC 61850, IEC 60870-5-104, DNP3, OPC UA, and MQTT/Sparkplug B. It has been deployed in real substations up to 230 kV and control centers with up to 70,000 tags.
| Feature | Details |
|---|---|
| License | GPL (open source) |
| Tag limit | Unlimited |
| OS | Windows, Linux, Docker |
| Web interface | Yes (Grafana-based dashboards) |
| Protocols | IEC 60870-5-104, IEC 60870-5-101, IEC 61850 (client), DNP3, OPC UA, MQTT/Sparkplug B, Modbus (via Telegraf) |
| Database | MongoDB (real-time), PostgreSQL/TimescaleDB (historian) |
| Language | C#, Node.js, Golang |
| Download | github.com/riclolsen/json-scada |
Best for: Power system SCADA, substations, control centers, multi-protocol environments. The only free SCADA with native IEC 61850 client support.
5. OpenSCADA
Modular open-source SCADA for Linux.
OpenSCADA is a highly modular and scalable open-source SCADA system designed primarily for Linux. It follows a flexible architecture where required modules can be added as needed.
| Feature | Details |
|---|---|
| License | GPL/LGPL (open source) |
| Tag limit | Unlimited |
| OS | Linux (primary), other Unix-based systems |
| Web interface | Optional (WebVision module) |
| Protocols | Modbus, OPC, GPIO, custom drivers |
| Database | SQLite, MySQL, PostgreSQL |
| Language | C++ |
| Download | oscada.org |
Best for: Research, custom automation projects, Linux-based industrial systems. Requires more technical skill than other platforms.
6. ScadaBR
Simple, user-friendly free SCADA.
ScadaBR is a web-based open-source SCADA system built on the Mango M2M platform. It supports Modbus RTU/TCP, OPC, and SNMP out of the box with visualization, alarms, and historical trends.
| Feature | Details |
|---|---|
| License | GPL (open source) |
| Tag limit | Unlimited |
| OS | Windows, Linux, macOS (Java/Tomcat) |
| Web interface | Yes |
| Protocols | Modbus RTU/TCP, OPC, SNMP, HTTP |
| Database | Derby (embedded), MySQL |
| Language | Java |
| Download | github.com/ScadaBR |
Best for: Small factories, education, quick prototyping. Easy to configure for real-time dashboards.
7. OSHMI
Open-source HMI for substations with IEC 61850.
OSHMI (Open Substation HMI) combines several open-source projects (Chromium, SVG/HTML5, PHP, Lua, Lib61850, OpenDNP3, Grafana, PostgreSQL) into a capable, web-based HMI system for substation automation.
| Feature | Details |
|---|---|
| License | GPL (open source) |
| Tag limit | Unlimited |
| OS | Windows, Linux |
| Web interface | Yes (HTML5/SVG in Chromium) |
| Protocols | IEC 60870-5-104, IEC 61850, DNP3, OPC UA |
| Database | PostgreSQL, SQLite |
| Language | Lua, PHP, C++ |
| Download | github.com/riclolsen/OSHMI |
Best for: Substation automation, protection relay HMI, control room displays. Used in real substations up to 230 kV.
8. Ignition (Free Trial)
Enterprise-grade SCADA with unlimited free trial.
Ignition by Inductive Automation is a commercial SCADA platform, but its trial version provides full access to all features with no tag limits. The trial resets every 2 hours — requiring a restart — but can be used indefinitely for learning and development.
| Feature | Details |
|---|---|
| License | Commercial (free trial, 2-hour reset) |
| Tag limit | Unlimited (during trial) |
| OS | Windows, Linux, macOS |
| Web interface | Yes (Perspective module) |
| Protocols | Modbus TCP, OPC UA, MQTT/Sparkplug B, Allen-Bradley, Siemens S7, BACnet, DNP3 |
| Database | MySQL, PostgreSQL, SQL Server, Oracle |
| Language | Java, Python (Jython scripting) |
| Download | inductiveautomation.com |
Best for: Learning enterprise-level SCADA concepts, system integrator training, proof of concept. The best way to learn industrial SCADA before committing to a paid license.
9. VTScada LIGHT
Professional SCADA with free 50-tag edition.
VTScada LIGHT is the free edition of the commercial VTScada platform by Trihedral. It provides up to 50 I/O tags at no cost with full alarm management, trending, and HMI design.
| Feature | Details |
|---|---|
| License | Freeware (50-tag limit) |
| Tag limit | 50 |
| OS | Windows |
| Web interface | Yes (Thin Client) |
| Protocols | Modbus, DNP3, OPC, BACnet, IEC 61850 (paid), Allen-Bradley |
| Database | Built-in historian |
| Language | Proprietary |
| Download | vtscada.com |
Best for: Small systems, demonstrations, training labs, hobby projects. Professional-grade quality in a free package.
10. IndigoSCADA
Lightweight SCADA with broad protocol support.
IndigoSCADA is an open-source SCADA/DCS system with support for Modbus, IEC 104, IEC 101, DNP3, and OPC. It includes a real-time database, HMI, and alarm management.
| Feature | Details |
|---|---|
| License | GPL (open source) |
| Tag limit | Unlimited |
| OS | Windows, Linux |
| Web interface | No (desktop only) |
| Protocols | Modbus, IEC 60870-5-104, IEC 60870-5-101, DNP3, OPC |
| Database | Real-time database (GIGABASE), PostgreSQL |
| Language | C++ |
| Download | sourceforge.net/projects/indigoscada |
Best for: Lightweight field SCADA, multi-protocol environments, legacy system integration.
11. WinTr SCADA
Free SCADA focused on HMI design.
WinTr is a free SCADA software for Windows with strong HMI design tools, scripting support (C#, VB.NET, JavaScript, Python), and built-in protocol drivers.
| Feature | Details |
|---|---|
| License | Freeware (200 tags free tier) |
| Tag limit | 200 (free), unlimited (paid) |
| OS | Windows |
| Web interface | No |
| Protocols | Modbus RTU/TCP, OPC DA, Siemens S7, MQTT, BACnet |
| Database | SQL Server, MySQL, SQLite |
| Language | C# |
| Download | wintrscada.com |
Best for: HMI design, scripting, education, small automation systems.
12. Fernhill SCADA
Client-server SCADA with free 100-tag edition.
Fernhill SCADA provides a free edition with up to 100 tags. It supports OPC DA, ODBC, and script-based data sources.
| Feature | Details |
|---|---|
| License | Freeware (100-tag limit) |
| Tag limit | 100 |
| OS | Windows, Linux |
| Web interface | No |
| Protocols | OPC DA, ODBC, scripting |
| Database | Built-in historian |
| Language | Proprietary |
| Download | fernhillsoftware.com |
Best for: Client-server SCADA training, small monitoring systems.
13. SZARP
Distributed SCADA for utilities.
SZARP is an open-source SCADA platform developed for energy system monitoring. It uses a distributed architecture where separate processes handle data acquisition, processing, and visualization.
| Feature | Details |
|---|---|
| License | GPL (open source) |
| Tag limit | Unlimited |
| OS | Linux, Windows |
| Web interface | Yes |
| Protocols | Modbus, custom |
| Database | Built-in (custom format) |
| Language | C/C++ |
| Download | szarp.org |
Best for: Energy systems, utilities, long-term monitoring.
14. How to Choose the Right Free SCADA Software
| If you need… | Choose… |
|---|---|
| A general-purpose free SCADA with no limits | Rapid SCADA |
| Web-based SCADA with IEC 104 and DNP3 | SCADA-LTS |
| Power system SCADA with IEC 61850 | JSON-SCADA or OSHMI |
| Enterprise-grade features for learning | Ignition (Trial) |
| A simple free SCADA for a small project (< 50 tags) | VTScada LIGHT |
| HMI design with scripting | WinTr SCADA |
| Lightweight multi-protocol SCADA | IndigoSCADA |
| Linux-based custom automation | OpenSCADA |
| Quick prototyping with web dashboards | ScadaBR |
15. Protocol Support Matrix
| Protocol | Rapid SCADA | SCADA-LTS | JSON-SCADA | OSHMI | Ignition | VTScada LIGHT | IndigoSCADA | WinTr |
|---|---|---|---|---|---|---|---|---|
| Modbus RTU | ✅ | ✅ | Via Telegraf | ❌ | ✅ | ✅ | ✅ | ✅ |
| Modbus TCP | ✅ | ✅ | Via Telegraf | ❌ | ✅ | ✅ | ✅ | ✅ |
| OPC UA | ✅ | ❌ | ✅ | ✅ | ✅ | ❌ | ❌ | ❌ |
| OPC DA | ❌ | ❌ | ❌ | ❌ | ✅ | ✅ | ✅ | ✅ |
| MQTT | ✅ | ❌ | ✅ | ❌ | ✅ | ❌ | ❌ | ✅ |
| IEC 60870-5-104 | ❌ | ✅ | ✅ | ✅ | ❌ | ❌ | ✅ | ❌ |
| IEC 60870-5-101 | ❌ | ✅ | ✅ | ❌ | ❌ | ❌ | ✅ | ❌ |
| DNP3 | ❌ | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ | ❌ |
| IEC 61850 | ❌ | ❌ | ✅ | ✅ | ❌ | ❌ | ❌ | ❌ |
| Siemens S7 | ❌ | ❌ | ❌ | ❌ | ✅ | ❌ | ❌ | ✅ |
| Allen-Bradley | ❌ | ❌ | ❌ | ❌ | ✅ | ✅ | ❌ | ❌ |
| BACnet | ❌ | ❌ | ❌ | ❌ | ✅ | ✅ | ❌ | ✅ |
| SNMP | ✅ | ✅ | Via Telegraf | ❌ | ❌ | ❌ | ❌ | ❌ |
Summary
Free SCADA software has made industrial automation accessible to everyone — from students to small utilities to substation engineers.
The key takeaways:
- Rapid SCADA is the best general-purpose free SCADA — no tag limits, open source, strong documentation
- SCADA-LTS is the best web-based option with IEC 104 and DNP3 support
- JSON-SCADA is the most powerful free platform for power systems — IEC 61850, IEC 104, DNP3, OPC UA, MQTT, and real substation deployments
- Ignition Trial gives you enterprise-grade features for free (with 2-hour reset)
- VTScada LIGHT and WinTr SCADA are the best freeware options for small projects
- If you need IEC 61850, your only free options are JSON-SCADA and OSHMI
For protocol-specific guides, see: