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Is Mermaid Validator 0 1 0 free to use?

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tangledgroup (@tangledgroup) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Mermaid Validator 0 1 0 by tangledgroup

Name: Mermaid Validator 0 1 0
Author: tangledgroup

Mermaid Validator 0 1 0

Lightweight Mermaid diagram syntax validator using the official mermaid parser with jsdom. Validates diagrams in markdown files, standalone .mmd files, directories, and stdin with JSON output support. Use when checking Mermaid diagram syntax for correctness before rendering, validating documentation containing Mermaid charts, or integrating diagram validation into CI/CD pipelines.

tangledgroup Updated Sep 17, 2026

File contents

mermaid-validate 1.0.1

Overview

@zabaca/mermaid-validate is a lightweight Mermaid diagram syntax validator that uses the official mermaid parser with jsdom for minimal DOM simulation. It validates diagram syntax accurately without requiring a full browser or puppeteer setup.

Use the wrapper script which handles runner detection (bun x preferred, npx -y fallback) and fixes the upstream tool's broken directory mode:

bash scripts/mermaid-validate.sh <file|directory|->

When to Use

Validating Mermaid diagrams embedded in markdown documentation before publishing
Adding diagram syntax checks to CI/CD pipelines or pre-commit hooks
Checking standalone .mmd files for syntax errors
Batch-validating all diagrams across a project's documentation directory

Core Concepts

Exit Codes

0 — All diagrams valid (or no mermaid blocks found)
1 — One or more diagrams have syntax errors
2 — Usage error (no input, missing file, unknown option)

Supported Inputs

Input	Description
`<file>`	Single `.md`, `.mmd`, `.markdown`, or `.mdx` file
`<directory>`	Recursively validates all matching files in the directory
`-`	Reads diagram code from stdin

Supported Diagram Types

All diagram types supported by mermaid: flowchart/graph, sequence, class, state, entity relationship, gantt, pie chart, and others.

CLI Options

Option	Description
`-h, --help`	Show usage help
`-q, --quiet`	Only output errors (suppress valid file markers)
`--json`	Output results as JSON

Usage Examples

Validate a single markdown file

bash scripts/mermaid-validate.sh README.md

Output for valid diagrams:

✓ README.md:block1
✓ README.md:block2

Summary: 2 valid, 0 invalid

Output for invalid diagrams:

✗ README.md:block1 (line 15)
  Parse error on line 1:
  ...

Summary: 1 valid, 1 invalid

Validate a standalone .mmd file

bash scripts/mermaid-validate.sh diagram.mmd

Validate all files in a directory

bash scripts/mermaid-validate.sh docs/

Validate from stdin

echo "graph TD; A-->B" | bash scripts/mermaid-validate.sh -

JSON output (for CI integration)

bash scripts/mermaid-validate.sh --json README.md

Output:

{
  "totalValid": 2,
  "totalInvalid": 0,
  "results": [
    { "file": "README.md:block1", "valid": true },
    { "file": "README.md:block2", "valid": true }
  ]
}

Quiet mode (only errors)

bash scripts/mermaid-validate.sh -q docs/

CI/CD integration

Use the exit code to fail pipeline runs when diagrams are invalid:

bash scripts/mermaid-validate.sh --json docs/

Exit code 0 passes, 1 fails — no additional tooling needed.

---name: mermaid-validator-0-1-0description: Lightweight Mermaid diagram syntax validator using the official mermaid parser with jsdom. Validates diagrams in markdown files, standalone .mmd files, directories, and stdin with JSON output support. Use when checking Mermaid diagram syntax for correctness before rendering, validating documentation containing Mermaid charts, or integrating diagram validation into CI/CD pipelines.---# mermaid-validate 1.0.1## Overview`@zabaca/mermaid-validate` is a lightweight Mermaid diagram syntax validator that uses the official `mermaid` parser with `jsdom` for minimal DOM simulation. It validates diagram syntax accurately without requiring a full browser or puppeteer setup.Use the wrapper script which handles runner detection (`bun x` preferred, `npx -y` fallback) and fixes the upstream tool's broken directory mode:```bashbash scripts/mermaid-validate.sh <file|directory|->```## When to Use- Validating Mermaid diagrams embedded in markdown documentation before publishing- Adding diagram syntax checks to CI/CD pipelines or pre-commit hooks- Checking standalone `.mmd` files for syntax errors- Batch-validating all diagrams across a project's documentation directory## Core Concepts### Exit Codes- `0` — All diagrams valid (or no mermaid blocks found)- `1` — One or more diagrams have syntax errors- `2` — Usage error (no input, missing file, unknown option)### Supported Inputs| Input | Description ||-------|-------------|| `<file>` | Single `.md`, `.mmd`, `.markdown`, or `.mdx` file || `<directory>` | Recursively validates all matching files in the directory || `-` | Reads diagram code from stdin |### Supported Diagram TypesAll diagram types supported by mermaid: flowchart/graph, sequence, class, state, entity relationship, gantt, pie chart, and others.### CLI Options| Option | Description ||--------|-------------|| `-h, --help` | Show usage help || `-q, --quiet` | Only output errors (suppress valid file markers) || `--json` | Output results as JSON |## Usage Examples### Validate a single markdown file```bashbash scripts/mermaid-validate.sh README.md```Output for valid diagrams:```✓ README.md:block1✓ README.md:block2Summary: 2 valid, 0 invalid```Output for invalid diagrams:```✗ README.md:block1 (line 15) Parse error on line 1: ...Summary: 1 valid, 1 invalid```### Validate a standalone .mmd file```bashbash scripts/mermaid-validate.sh diagram.mmd```### Validate all files in a directory```bashbash scripts/mermaid-validate.sh docs/```### Validate from stdin```bashecho "graph TD; A-->B" | bash scripts/mermaid-validate.sh -```### JSON output (for CI integration)```bashbash scripts/mermaid-validate.sh --json README.md```Output:```json{ "totalValid": 2, "totalInvalid": 0, "results": [ { "file": "README.md:block1", "valid": true }, { "file": "README.md:block2", "valid": true } ]}```### Quiet mode (only errors)```bashbash scripts/mermaid-validate.sh -q docs/```### CI/CD integrationUse the exit code to fail pipeline runs when diagrams are invalid:```bashbash scripts/mermaid-validate.sh --json docs/```Exit code `0` passes, `1` fails — no additional tooling needed.

Frequently asked questions