Sometimes we get the question from students and non-commercial users: Why pay for Sigasi Visual HDL? Adding the claim: TerosHDL does “the same” for free
TL;DR
We wanted to factcheck that claim, did a full investigation and made a comparison feature by feature on the differences between Sigasi Visual HDL and TerosHDL. This comparison was made based on publicly available documentation, our friends at ChatGPT, Gemini, Claude, Perplexity,… and user feedback. It becomes clear that TerosHDL does not match the capabilities and features of Sigasi Visual HDL and that the claim is false.
Intro: “Free” is not the same as “without costs”
First of all, “free” means that the license to use the software doesn’t come with an upfront license cost. Setting up an HDL development environment, is expensive if you need time to figure it all out by yourself. Therefore, our excellent support team is glad to give professional users all the support they need included in the license fee to set-up a project hassle free. No more searching, asking, restarting, and… losing time and money. We guarantee a smooth start with Sigasi. That’s why we’ve integrated a tutorial in the VS Code Extension that is free to use for commercial and non-commercial (Community Edition) users.
If you are a commercial user and you want to try Sigasi before buying, you can REQUEST A TRIAL (only available with a company e-mailaddress) and we will give you a full demo to assist you with setting up your project. Click here to get going with your demo and full featured trial license.
If you are a student or non-commercial user, you can immediately download Sigasi Visual HDL Community Edition for FREE from the VS Code marketplace. Make sure you have Visual Studio Code installed. You can get VS Code here . Once you have VS Code installed, add the Sigasi extension Community Edition for FREE and enable all features of Sigasi Visual HDL (except CLI).
Feature comparison
🧩 Integration
| TerosHDL | Sigasi Visual HDL | |
|---|---|---|
| VS Code IDE Extension | ||
| Advanced Scalable Set-up | ||
| Project Management Config Tools | ||
| Semantic, Hierarchy-aware Code Navigation | ||
| Professional Project Setup Support | ||
| Git Version Control |
🧠 Intelligent Code Assist
| TerosHDL | Sigasi Visual HDL | |
|---|---|---|
| Folding | ||
| Semantic Highlighting | ||
| (Quick) Outline | ||
| Structural Selection | ||
| Open Design Unit | ||
| Find References | ||
| Go to Implementation | ||
| (Ranged) Formatting/indenting | ||
| Elaboration Hierarchy View | ||
| Syntax Checking (*) | ||
| Real-time (Syntax) Error Checking | ||
| Smart Indentation | ||
| Full Autocomplete | ||
| Context-aware IntelliSense Autocomplete | ||
| Semantic Occurrence Highlighting | ||
| Progress Reporting | ||
| Memory Monitoring | ||
| Go to Definition/Declaration in VHDL | ||
| Go to Definition/Declaration in Verilog/SV | ||
| Configurable Formatting | ||
| Class Hierarchy | ||
| Elaboration Hierarchy View | ||
| Libraries View | ||
| Code Lenses | ||
| Hovers | ||
| Hover Actions |
(*) TerosHDL depends on seperate tools for syntax checking
✅ Compliance Assist
| TerosHDL | Sigasi Visual HDL | |
|---|---|---|
| Quick Fixes | ||
| Linting (*) | ||
| Real-time Linting | ||
| Cross-file Linting |
(*) TerosHDL depends on seperate tools for linting
✨ Design Assist
| TerosHDL | Sigasi Visual HDL | |
|---|---|---|
| Tools & Libraries | ||
| Signature Helper | ||
| Documentation (Pre)View | ||
| Semantic Errors | ||
| Rename Refactoring for VHDL | ||
| Rename Refactoring for Verilog/SV | ||
| Net Search | ||
| Template Autocomplete | ||
| Context-aware Template Autocomplete | ||
| Preprocessor Autocomplete | ||
| Preprocessor View | ||
| Preprocessor Hover |
🖼️ Graphic Assist & Visualization
| TerosHDL | Sigasi Visual HDL | |
|---|---|---|
| Dependencies Diagram | ||
| Block Diagram (*) | ||
| Finite State Machines (FSM) Diagram | ||
| Real-time & Interactive FSM Diagram | ||
| Built-in Design Graphics Export | ||
| Design Hierarchy Export | ||
| Interactive Outline View |
(*) TerosHDL depends on seperate tools for Block Diagram View
🛠 Verification Assist
| TerosHDL | Sigasi Visual HDL | |
|---|---|---|
| UVM Linting | ||
| UVM Topology View | ||
| UVM Diagram |
📚 Doc Assist
(only in Sigasi Visual HDL Enterprise Edition)
| TerosHDL | Sigasi Visual HDL | |
|---|---|---|
| Single File Doc Generation | ||
| Full Project Documentation Generation |
💸 CLI Task Assist
(only in Sigasi Visual HDL Enterprise Edition)
| TerosHDL | Sigasi Visual HDL | |
|---|---|---|
| CLI Lint Reporting | ||
| CLI Documentation Generation | ||
| CLI Dependency Generation | ||
| CLI Diagram Generation | ||
| CLI Library Extraction | ||
| CLI VHDL Formatting |
📋 Support
| TerosHDL | Sigasi Visual HDL | |
|---|---|---|
| User Manual | ||
| Local Assistance in USA | ||
| Local Assistance in Germany & DACH | ||
| Local Assistance in UK, Ireland & Nordics | ||
| Local Assistance in India | ||
| Local Assistance in Türkiye | ||
| Local Assistance in Benelux & France | ||
| Professional Support |
🎯 Conclusion
- Sigasi Visual HDL is a purpose-built HDL engineering workspace for professional FPGA and ASIC development. It brings deep, on-the-fly semantic understanding to VHDL, (System)Verilog and mixed language projects inside VS Code; so you can create, explore, and maintain RTL with immediate feedback and richer design insight.
As you type, Sigasi continuously parses and analyzes your project in context (types, scopes, hierarchy, dependencies). That powers fast navigation, safe refactoring, compliance checks, and live design visualizations—helping teams reduce avoidable churn while keeping the rest of their toolchain intact. Core diagnostics are deterministic and reproducible, which makes the feedback reliable for both individuals and teams.
Licensing & deployment. Sigasi Visual HDL supports both node-locked and floating licenses. Project set-up support is available when needed.
ROI, stated credibly. Most teams justify Sigasi by measuring fewer avoidable issues reaching simulation/CI, less review churn, and faster navigation/refactoring in large codebases. A short pilot on an active repo typically makes the value measurable within weeks—without needing blanket “X hours saved” claims.
About Sigasi. Sigasi is a privately held company founded in 2008, focused on improving day-to-day workflows for chip design and verification engineers. On average four major releases are made per year.
TerosHDL is a lightweight, underpowered open-source IDE for FPGA students, hobbyists, and independent designers with limited resources that can’t spend money on a tool that makes them work faster and better. It lacks semantic understanding and deeper design insights. About Teros. Teros Technology was funded through the European Commission’s Next Generation Internet programme, under grant agreement No 957073. On average, one major release was done per year. Last update was in March 2025. There is no information about a planned future release.
Sigasi Community Edition is the free version of Visual HDL for students, academics and non-commercial users so they can learn and experience the advantages of Sigasi when designing a chip. The only difference between CE and the Professional Edition is that Talkback must be enabled in CE. The Community Edition can be downloaded here
Start to learn chip design like a pro
As a student or non-commercial user, don’t hesitate to use Sigasi Visual HDL Community Edition free of charge. You will get the full experience and the quality of your RTL will be so much better. Design your next chip faster and better!