Syntaxor

BNF playground

MENU

Grammar Workspace

SELECT TEST RULE

ENTER STRING TO TEST

Status

No warnings.

Syntax Diagram

SELECT RULE

Enter a valid grammar to build the diagram.

© 2026 Neil Kendall More @ www.korovatron.co.uk

Parse Tree

Tasks

Loading tasks...

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About Syntaxor

Syntaxor is a Backus Naur Form (BNF) playground for A Level Computer Science: build grammar rules, test strings, and visualise syntax and parse trees.

Version:

Show this on start-up

© 2026 Neil Kendall - More @ www.korovatron.co.uk

Quick Help

Examples
Open the top-right menu and expand Examples to load a starter grammar.

Grammar Workspace
Type rules in BNF. Empty string markers entered as "" are converted to ε automatically.

Testing
Choose a rule with SELECT TEST RULE, then use ENTER STRING TO TEST to check if the string is accepted, and optionally display the parse tree.

Status
The Status badge shows whether there are grammar issues (red outline) or no issues (white outline).

Syntax Diagram
Use SELECT RULE to switch the displayed diagram between grammar rules.

Clear Workspace
Use the red dustbin button in Grammar Workspace to clear grammar and test input.