Sentence Diagrammer

Parse English sentences and visualize their grammatical structure as an interactive syntax tree.

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How it works

This tool parses English sentences using a rule-based constituency grammar and displays the result as a syntax tree (phrase structure tree). All processing runs entirely in your browser.

• Part-of-speech tagging: each word is tagged with its likely grammatical role (noun, verb, adjective, etc.) using a built-in lexicon and heuristic rules.
• Phrase structure: tagged words are grouped into phrases — noun phrases (NP), verb phrases (VP), prepositional phrases (PP), and adjective phrases (AdjP) — following standard English grammar patterns.
• Sentence node (S): the top-level node splits into subject (NP) and predicate (VP), the fundamental division of English sentence structure.
• Modifiers: adjectives, adverbs, and prepositional phrases are shown as branches attached to the words or phrases they modify.
• Compound sentences: sentences joined by coordinating conjunctions (and, but, or) are shown with both clauses under a top-level node.

The parser handles common English structures but may not correctly diagram every sentence. Complex or ambiguous constructions may produce approximate results.

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