Finite automata

DFA & NFA drawer · Chapter 1

Automaton

Color states: start, accepting

Selection

Nothing selected. Click a state or an arrow to edit it.

Input string

Test many strings at once

Regular expression

+ means Alphabet Σ

Regex → NFA

Sipser's construction: an NFA for each piece, joined with ε-moves.

Strings in the language

Compare two expressions

Drawing → regex

Turns the automaton on the canvas into a regular expression by removing states from a generalized NFA (GNFA).

Draw DFA and NFA diagrams online

DeltaDraw is a free finite automata drawing tool. Sketch a deterministic (DFA) or nondeterministic (NFA) finite automaton, test strings on it, convert an NFA to a DFA, minimize it, and export a clean state diagram as PNG, SVG or LaTeX (TikZ). It runs in your browser with nothing to install and no sign-up.

How to draw

Add a state: double-click empty space, or pick the State tool and click.
Add a transition: hold Shift and drag from one state to another, or use the Transition tool. Drag back onto the same state for a self-loop.
Start arrow: tick Initial state in the panel, or Shift-drag from empty space onto a state.
Accepting state: double-click a state, or tick Accepting state.
Label: select something and type. Separate symbols with commas, like 0,1.
Curve an arrow: drag the middle of a transition. Drag a self-loop to rotate it.
Export: press Export and download PNG, SVG, LaTeX or JFLAP.

Label shortcuts

Type	Shows
`q_0`	q₀
`q_{10}`	q₁₀
`a^*`	a^*
`\epsilon` or `\eps`	ε
`\lambda`, `\Sigma`, `\delta`	λ, Σ, δ
`\emptyset`	∅

Any Greek letter works the same way, for example \alpha or \Gamma.

Keyboard

`Shift` + drag	New transition
`Delete`	Delete selected
`Backspace`	Erase a label character
`Ctrl` `Z`	Undo
`Ctrl` `Shift` `Z`	Redo
`Ctrl` `S`	Save file
`Esc`	Deselect, back to Select tool
Mouse wheel	Zoom

Features

DFA, NFA and ε-NFA state diagrams with curved arrows and self-loops
Step-by-step string simulation with highlighted states
NFA to DFA conversion (subset construction)
DFA minimization
Automatic transition table
Export to PNG, SVG, LaTeX/TikZ and JFLAP (.jff)
Open JFLAP files, save and reopen your own drawings
Auto-save in your browser, light and dark theme