How Browser-Based Link Validation Actually Works

Feb 21, 2026 Web APIs

AxelBase operates completely within your browser, leveraging native web APIs to parse content and test links without any server involvement.

1. Local Parsing & Extraction

First, the tool reads your input as plain text. It uses a lightweight parser to scan for patterns defined in the CommonMark specification. This includes:

  • Standard inline links [text](url)
  • Reference-style definitions [id]: url
  • Autolinks wrapped in <brackets>
  • Image sources inside ![]() tags

2. The Validation Engine

Once URLs are extracted, the checker sends HTTP requests directly from your browser using the native fetch() API. To optimize speed and save your bandwidth, the engine follows a specific hierarchy:

  1. HEAD Request: We first ask the server for headers only. This is ultra-fast as it doesn't download the whole page.
  2. GET Fallback: If a server blocks HEAD requests, we gracefully switch to a GET request, often with a Range header to stop after the first few bytes.

During this phase, redirects are followed automatically up to a configurable limit, and timeouts are enforced to ensure one slow website doesn't hang your entire scan.

3. Handling Edge Cases & Privacy

Relative paths and internal anchors (#heading-name) are handled by simulating a virtual project structure. You can define a "Base Path" so the tool knows how to resolve links like ./docs/setup.md just like GitHub or your production site would.

Privacy by Design

No request is ever sent to an AxelBase server. No analytics endpoints are pinged. Your documentation remains strictly between your browser and the target links you are checking.

Next we will cover practical steps to get your first validation results quickly and accurately.