A web application for simulating combinational and sequential digital circuits based on directed graphs.
Circulogi is an open-source web simulator built with Nuxt.js that represents digital circuits as directed graphs instead of traditional schematics. This approach provides a more abstract and readable representation, making it easier for students and educators to understand, analyze, and debug digital logic circuits.
- Directed graph visualization — Logic gates and connections are rendered as an interactive directed graph, showing boolean sub-expressions directly on each node's output
- Combinational circuits — Supports AND, OR, NOT, XOR, NAND, NOR, and XNOR gates
- Sequential circuits — Supports D, T, SR, and JK flip-flops with clock components
- Real-time simulation — Signal propagation is computed on every user interaction using a BFS (Breadth-First Search) algorithm
- Boolean expression labels — Each gate output automatically displays its boolean sub-expression (e.g.
~(b | a),~(~(b | a)) ^ d) - Cloud save & shareable links — Circuits are automatically saved and can be shared via a public URL
- Component menu — Add inputs, outputs, logic gates, flip-flops, clocks, and text notes from a bottom toolbar
- Export as image — Download a snapshot of the current circuit
- Node.js ≥ 18
- PostgreSQL database (or a Supabase project)
# Clone the repository
git clone https://github.com/pedrobealves/circulogi.git
cd circulogi
# Install dependencies
npm install
# Configure environment variables
cp .env.example .env
# Edit .env with your database connection string and auth settings
# Run database migrations
npx prisma migrate dev
# Start the development server
npm run devThe app will be available at http://localhost:3000.
Circulogi is structured as a full-stack Nuxt.js application following Domain-Driven Design (DDD) with Nuxt layers:
| Layer | Responsibility |
|---|---|
Auth |
Authentication, registration, session management |
Circuit |
Circuit CRUD, global state management |
Simulation |
Graph rendering, BFS signal propagation, event handling |
Website |
Landing page and navigation |
Common |
Shared components, utilities, and assets |
| Category | Technology |
|---|---|
| Framework | Nuxt.js (Vue 3 + SSR) |
| State management | Pinia |
| Graph rendering | v-network-graph |
| Database ORM | Prisma |
| Database | PostgreSQL (via Supabase) |
| Background processing | Nuxt Workers + WebAssembly (Rust) |
| Hosting | AWS Amplify |
| DNS / Protection | Cloudflare |
| Testing | Vitest |
Digital circuits are modeled as directed graphs where:
- Nodes represent logic gates (AND, OR, XOR…), flip-flops (D, T, SR, JK), inputs, outputs, and clock signals
- Edges represent wire connections carrying logical signals
When a user clicks an input node or when a clock fires, a BFS traversal starts from that node and propagates the logical value through all connected nodes according to their gate type. Each node's color is updated to reflect its current state:
- 🟢 Green = logic
1(HIGH) - 🔴 Red = logic
0(LOW)
Boolean sub-expressions are computed and displayed as labels on intermediate nodes (e.g. b & a, ~(b | a), ~(~(b | a)) ^ d), giving users a step-by-step view of how the signal transforms through the circuit.
To prevent processing loops in sequential circuits, the BFS tracks visited nodes and handles flip-flop state storage separately.
AND · OR · XOR · NAND · NOR · XNOR · NOT
D · T · SR · JK
Input · Output · Clock · Text Note
User
├── id UUID
├── email String (unique)
├── password String
└── circuits Circuit[]
Circuit
├── id UUID
├── name String
├── content JSON (graph nodes + edges)
├── version String
├── cover String (auto-generated preview image URL)
├── createdAt DateTime
└── userId UUID → User
Contributions are welcome! Feel free to open issues or pull requests.
- Fork the repository
- Create a feature branch:
git checkout -b feature/my-feature - Commit your changes:
git commit -m 'Add my feature' - Push to the branch:
git push origin feature/my-feature - Open a Pull Request
This project is licensed under Creative Commons BY-NC-ND 4.0 — you may share it with attribution, but may not modify or use it commercially.
Circulogi was developed as an undergraduate thesis (Trabalho de Conclusão de Curso) for the Computer Engineering program at Universidade Tecnológica Federal do Paraná (UTFPR), Cornélio Procópio campus, in 2025.