Syntax Tree Generator: Type a Sentence, Get a Labeled Tree

A syntax tree — also called a syntactic tree, parse tree or phrase structure tree — is a diagram of how the words of a sentence group into phrases and clauses. Read it from the top down:

• Root: the clause node — S in traditional and X-bar trees, CP and TP in Minimalist ones.
• Phrase nodes: NP, VP, PP, AP and so on; each groups a head with the words that depend on it.
• Head: the word that gives a phrase its category, such as the verb in a VP.
• Terminals: the words of your sentence, left to right, along the bottom.
• Traces: t_i marks where a moved phrase started; a dashed arrow shows the move.

In linguistics, syntax tree, parse tree and phrase structure tree usually mean the same diagram. In computer science they differ: a parse tree (concrete syntax tree) shows every grammar rule used to derive a string, while an abstract syntax tree (AST) keeps only the structure a compiler needs. This tool is built for the linguistics kind. It will also draw a parse tree for a simple arithmetic expression or grammar string, but it doesn't parse program code.

To draw a syntax tree, label each word with its category, group heads with their dependents into phrases from the bottom up, build the verb phrase, then join the subject and the verb phrase under the clause node.

1. Label each word with its category: N, V, Det, P, Adj, Adv.
2. Group each head with its dependents into phrases, bottom-up: Det + N → NP; P + NP → PP.
3. Build the VP around the main verb and its objects.
4. Join the subject NP and the VP under S (or TP in Minimalist trees).
5. Test every phrase with substitution, movement and coordination, as in the checklist further down.

The chef prepared the dish comes out as:

[S [NP [Det The] [N chef]] [VP [V prepared] [NP [Det the] [N dish]]]]

Pick the one your course or paper uses. The Tree Style menu sets the defaults below; specific instructions in the prompt ("use DP", "show the trace") are followed, and a framework you name on purpose in the prompt wins over the menu.

For example, "What did you see?" might come out as (this is the tree in the examples below):

[CP [DP_i [D What]] [C' [C did_j] [TP [DP [D you]] [T' [T t_j] [VP [V see] [DP t_i]]]]]]

— two movements, two traces, two dashed arrows in the drawing.

Using Carnie's Syntax: A Generative Introduction? Its trees combine X-bar levels with DP, TP and CP: pick X-bar and write "use DP, TP and CP" in the prompt.

Run the standard constituency tests on each phrase the tree claims:

1. Substitution: can a pro-form (it, they, there, do so) replace the string?
2. Movement: can you front it, or put it in a cleft ("It was ___ that…")?
3. Coordination: can you join it to a similar string with "and"?
4. Answer fragment: can it stand alone as the answer to a question?
5. Word check: does every word of your sentence appear once, in order?
6. Framework check: do the labels (NP or DP, S or TP) and bar levels match your course?

If a phrase fails the tests, tell the generator what to change — "the PP modifies the noun, not the verb" — and draw it again.

• Right-to-left languages: Hebrew and Arabic are not laid out right-to-left yet.
• Chinese, Japanese and Korean: these go to the image model instead of the code renderer, so proofread the characters.
• LaTeX: paid plans can copy forest code or labeled brackets (Copy code); movement arrows are left out, so add them with \draw if you need them. You can also place the SVG in a LaTeX document.
• Sketch or photo input: a tree you upload as a sketch or photo is redrawn by the image model, so proofread every label.
• Contested analyses: where frameworks disagree, the model picks one. Say which analysis your course uses.

How Vizcept draws figures explains what the code guarantees and what it doesn't.

Pick the tool that matches what you already have. Each kind of syntax tree tool solves a different problem.

Each example in the gallery below, with the labeled bracket string the tool produced for it. Paste any of them into a bracket-notation tool to compare.