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FastX402 HTML Heading Tree Extractor
x402
FastX402 HTML Heading Tree Extractor is a paid API for AI agents from fastx402.tools, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-20).
Parses an HTML document or fragment and returns a nested tree of all heading elements (h1–h6) with their text, level, depth, id, and hierarchical children.
Price / call$0.001
Success—
StatusUnknown
How this service works
200 pay-per-call tools for AI agents, from $0.001 per request in USDC on Base or Solana with x402. No account, no API key.
Output
Returns a JSON object containing a 'headings' array of nested heading nodes. Each node includes: 'text' (heading content), 'level' (h1=1 through h6=6), 'depth' (nesting depth starting at 0 for top-level), 'id' (the element's HTML id attribute if present), and 'children' (array of sub-heading nodes with the same structure). The tree mirrors the hierarchical document outline implied by the HTML heading tags.
Example use cases
Table of contents generation
“I have this full HTML page and I need to generate a table of contents from its headings — can you pull out all the h1 through h6 tags and return them in a nested tree structure? Here's the HTML: '<article><h1 id="main">Guide to APIs</h1><h2 id="basics">Basics</h2><h3>Auth</h3><h2 id="advanced">Advanced</h2></article>'”
Document outline for accessibility audit
“Take this HTML fragment and extract its heading hierarchy so I can check whether the heading levels are structured correctly for accessibility: '<div><h1>Report</h1><h3>Summary</h3><h2>Details</h2><h4>Notes</h4></div>'”
Navigation menu generation from blog post
“Here's the raw HTML of a blog post — pull out all the headings as a nested tree with their ids and text so I can build a sidebar navigation menu from them: '<h1 id="top">Machine Learning Basics</h1><h2 id="supervised">Supervised Learning</h2><h3 id="regression">Regression</h3><h2 id="unsupervised">Unsupervised Learning</h2>'”
Technical details
Endpoint
GEThttps://fastx402.tools/html-heading-tree?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need a structured, hierarchical tree representation of headings from raw HTML — not just a flat list. It is ideal for generating tables of contents, building navigation menus, auditing document structure, or analyzing heading hierarchy. Prefer this over manual regex approaches when you need proper nesting with depth and id metadata. Pay-per-call with no account or API key required makes it ideal for one-off agent tasks.
Side effects
- Missing or empty 'html' query parameter — API returns an error requiring the field
- HTML with no heading elements — returns an empty headings array
- Malformed HTML — parser may produce unexpected or empty tree depending on severity
- Very large HTML documents may time out or exceed request limits
- Non-UTF-8 encoded HTML may cause parsing errors
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"headings": [
{
"id": "intro",
"text": "Introduction",
"depth": 0,
"level": 1,
"children": [
{
"id": "bg",
"text": "Background",
"depth": 1,
"level": 2,
"children": [
{
"text": "History",
"depth": 2,
"level": 3,
"children": []
}
]
},
{
"text": "Methods",
"depth": 1,
"level": 2,
"children": []
}
]
},
{
"text": "Conclusion",
"depth": 0,
"level": 1,
"children": []
}
]
}
}Tags
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