Free State Diagram Generator
Create state diagrams and state machine diagrams with our free AI tool. Design UML state diagrams, FSM diagrams, Moore and Mealy machines instantly.
What is a State Diagram?
A state diagram (also called a state machine diagram or statechart) is a visual representation of all possible states a system can be in and the transitions between those states. Each state represents a condition or situation, and arrows show how the system moves from one state to another based on events or conditions.
State diagrams help you:
- Model behavior — Define how systems respond to events
- Find edge cases — Identify missing transitions and invalid states
- Document logic — Communicate complex behavior to developers and stakeholders
- Design software — Plan UI flows, protocols, and embedded systems
Common in UML modeling, state diagrams are essential for designing anything with distinct modes or phases—from vending machines to authentication flows.
Types of State Diagrams
UML State Diagrams
The standard notation for modeling object behavior in software engineering. UML state diagrams show states as rounded rectangles, transitions as arrows, and include initial/final states, guards, and actions.
Finite State Machine (FSM) Diagrams
Used in computer science and digital logic design. FSM diagrams represent systems with a finite number of states, inputs, and deterministic transitions. Common in protocol design and embedded systems.
Moore vs Mealy Machines
Two types of finite state machines:
- Moore machines — Outputs depend only on the current state
- Mealy machines — Outputs depend on current state AND input
Moore machines are simpler to design; Mealy machines often require fewer states.
State Transition Diagrams
A general term for any diagram showing states and transitions. Often used interchangeably with state diagram or statechart.
Common State Diagram Examples
Vending Machine
States: Idle, Accepting Coins, Dispensing, Returning Change. Transitions triggered by coin insertion, product selection, and timeouts.
Traffic Light System
States: Green, Yellow, Red (and variations for turn signals). Timer-based transitions with sensor inputs for traffic-responsive systems.
TCP Connection
States: CLOSED, LISTEN, SYN_SENT, ESTABLISHED, FIN_WAIT, TIME_WAIT, and more. The classic example for network protocol state machines.
User Authentication
States: Logged Out, Attempting Login, Authenticated, Session Expired, Locked Out. Transitions based on credentials, timeouts, and failed attempts.
These examples work perfectly with our AI generator—just describe the system and get a complete state diagram.
Create State Diagrams with AI
Describe your system's behavior and let AI generate a complete state diagram with all states and transitions.
How it works:
- Describe your system: "State diagram for a door lock with states: Locked, Unlocked, and Alarmed. Correct code unlocks, wrong code three times triggers alarm."
- AI generates the state machine with proper notation
- Download in high resolution for documentation
Works for any state machine:
- Software UI flows
- Protocol designs (TCP, HTTP)
- Embedded systems
- Game logic
- Business process states
Frequently Asked Questions
One Diagram. Different Styles.
Don't settle for generic visuals. Match your diagram's aesthetic to your brand identity with our Style Picker.
Content-Based
Corporate Clean
Modern Tech
Editorial / News
3D Isometric
Blueprint
Hand-Drawn
Cyberpunk
Paper Cutout
Retro Pixel
Content-Based
Corporate Clean
Modern Tech
Editorial / News
3D Isometric
Blueprint
Hand-Drawn
Cyberpunk
Paper Cutout
Retro Pixel
Auto-scrolling showcase • Hover to pause • Click to create