Skip to content
Aback Tools Logo

Link Header Parser

Parse HTTP Link headers for rel=preload, preconnect, dns-prefetch, canonical, and more. Paste any Link header value to instantly extract URIs, link relations, and parameters with smart validation and actionable optimization suggestions. All parsing happens locally in your browser - your data remains private, no signup required.

Parse Link Header

Paste one or more Link header values to extract URIs, rel types, and parameters. Validates syntax and provides optimization suggestions.

Examples:

Paste a Link HTTP header value above and click Parse Header to extract all URIs, link relations, and parameters.

Supports RFC 8288 Web Linking format. Try one of the example presets to see how it works.

Why Use Our Link Header Parser?

Instant Link Header Parsing

Paste any Link HTTP header value and instantly extract every URI, link relation (rel), and parameter. Our RFC 8288-compliant parser handles angle-bracket URIs, quoted and unquoted values, comma-separated multi-link headers, and complex parameter combinations effortlessly.

Categorized by Relation Type

Parsed links are automatically grouped into meaningful categories: Resource Hints (preload, prefetch, preconnect), SEO (canonical), Pagination (next, prev), Stylesheets, Icons, and more. Each category is colour-coded for quick visual scanning of your Link headers.

Smart Validation & Suggestions

The parser validates syntax and provides actionable suggestions: missing "as" attribute on preload links, unexpected parameters, unencoded spaces in URIs, and non-standard URL formats. Helps you optimise your resource hints and prevent common misconfigurations.

100% Private & Client-Side

All Link header parsing happens entirely in your browser. Your header data never leaves your device - no uploads, no server processing, no logging. Use our Link header parser with complete privacy for any HTTP headers you need to inspect.

Common Use Cases for Link Header Parser

Web Performance Optimisation

Audit resource hints (preload, prefetch, preconnect) in your HTTP response headers to ensure they are properly configured. Verify that preload links include the required "as" attribute, that preconnect URLs have the correct CORS attributes, and that prefetch targets are appropriate for your user flow.

SEO & Canonical URL Verification

Verify that canonical link headers point to the correct URLs and that alternate hreflang links are properly formatted for international SEO. Catch mismatched canonical URLs, missing hreflang annotations, or incorrect language tags before they affect search rankings.

API Pagination Debugging

Inspect pagination link headers (rel=first, rel=prev, rel=next, rel=last) in REST API responses. Verify that the pagination chain is complete and that all URIs are correctly formatted. Essential when building or consuming paginated API endpoints.

Development & Testing

When developing web applications, quickly parse and validate Link headers served by development servers, CDN configurations, or application middleware. Verify that redirect responses include proper link headers for resource hints and SEO metadata.

Performance Budget Audits

Review preload and preconnect headers as part of your performance budget analysis. Check that resource hints target the most critical assets, that there are no redundant or conflicting hints, and that the number of preload requests stays within your budget limits.

HTTP Response Header Analysis

When analysing HTTP response headers from any web service, use the Link header parser to decode and understand the link relations being advertised. Useful for security assessments, integration testing, and understanding server-to-client relationship hints.

Understanding HTTP Link Headers

What is a Link HTTP Header?

The Link header is an HTTP response header defined in RFC 8288 (Web Linking) that allows a server to convey link relations to the client without requiring HTML parsing. It follows the format<URI>; rel="type"; param="value"and can include multiple links separated by commas. Link headers are widely used for resource hints (preload, preconnect), SEO metadata (canonical, alternate), pagination (next, prev), and many other web linking purposes.

Unlike HTML <link> elements, Link headers can be set in server configuration, middleware, or application code without modifying HTML templates. This makes them especially useful for performance optimisation, dynamic resource hints, and API responses where HTML is not present.

How Our Link Header Parser Works

Our Link header parser processes RFC 8288-formatted headers entirely in your browser.

  1. Splitting - The parser splits comma-separated links while respecting angle brackets to avoid splitting URIs that contain commas. Each segment becomes a separate link entry.
  2. URI extraction - For each link, the URI enclosed in angle brackets <...> is extracted. The parser validates the URI format and provides warnings for common issues like unencoded spaces or non-standard formats.
  3. Parameter parsing - Parameters after the URI are parsed using a regex that handles quoted values (rel="preload"), unquoted values (as=style), and boolean parameters (crossorigin without a value). The rel parameter is identified and used to categorise the link.

Common Link Relation Types Explained

Our Link header parser recognizes and categorises these common link relations:

  • Resource Hints - preload downloads critical resources early (requires as attribute for priority handling), preconnect establishes early connections to origins, prefetch fetches resources for future navigation, and dns-prefetch resolves domain names early.
  • SEO Relations - canonical indicates the preferred URL for duplicate content, and alternate with hreflang specifies language/regional variants for international SEO.
  • Pagination - first, prev, next, and last define a paginated resource sequence, commonly found in REST API responses.
  • Other Relations - stylesheet links CSS files, icon specifies favicons, manifest points to the PWA manifest, and license links to licensing information.

Privacy & Local Processing

Our Link header parser processes all data entirely in your browser using JavaScript. The Link header values you paste are never sent to any server, never stored in any database, and never leave your device. This ensures complete privacy for any HTTP headers or URLs you choose to inspect.

Link headers are commonly exposed in HTTP responses that pass through CDNs, proxies, and monitoring tools. However, you may be inspecting internal development headers, staging environment responses, or proprietary API configurations. Our tool guarantees that your data stays completely private and secure throughout the parsing process.

Related Tools

Request Header Builder

Build a custom HTTP request with specific headers, method, and body. See the raw request format generated in real-time.

HTTP Header Checker

Fetch any URL and display all response headers with descriptions. Shows status code, content-type, cache-control, server, and more.

Content Security Policy Validator

Paste a CSP header and validate it. Check for missing directives, unsafe-inline, unsafe-eval, and recommended policies.

CORS Preflight Tester

Send a CORS preflight (OPTIONS) request to any URL with custom origin, method, and headers. Analyzes Access-Control-* response headers.

Frequently Asked Questions About Link Header Parser

A Link HTTP header is a response header defined in RFC 8288 (Web Linking) that conveys link relations between the current resource and other resources. It follows the format `<URI>; rel="type"; param="value"` and can include multiple comma-separated links. Link headers are commonly used for resource hints (preload, preconnect), SEO metadata (canonical URLs, alternate pages), and API pagination (next, prev, first, last links).

Link headers serve the same purpose as HTML `<link>` elements but can be set in server configuration, middleware, or application code without modifying HTML templates. This makes Link headers ideal for dynamic resource hints, server-driven performance optimisation, and API responses where HTML is not generated. Link headers also work for non-HTML resources like API JSON responses, CSS files, and script responses.

RFC 8288 (obsoleting RFC 5988) defines the Web Linking format for HTTP. A Link header value consists of a URI enclosed in angle brackets (`<URI>`), followed by semicolon-separated parameters. The `rel` parameter specifies the link relation type (required), and additional parameters like `as`, `type`, `crossorigin`, `media`, and `hreflang` provide context. Multiple links can be included in a single header separated by commas.

Yes. All Link header parsing is performed entirely in your browser using client-side JavaScript. The header values you paste are never sent to any server, never stored in any database, and never leave your device. The tool works completely offline after the initial page load, ensuring complete privacy for any HTTP headers you choose to inspect.

The `as` attribute on a preload link tells the browser what type of resource is being preloaded (script, style, image, font, fetch, document, worker, etc.). This is required because browsers use the `as` value to set the correct priority, Content-Type, and Accept headers for the request, and to apply the correct Content Security Policy (CSP) checks. Without `as`, the browser treats the preload with low priority and may issue a warning in the console.

Our Link header parser supports all standard link relation types defined in the IANA Link Relations registry. It specifically provides detailed descriptions for: resource hints (preload, prefetch, preconnect, dns-prefetch, prerender, modulepreload), SEO relations (canonical, alternate), pagination (first, prev, next, last), stylesheets, icons, discovery (manifest, search), and more. Unknown relation types are categorized as "Other" with the raw rel value displayed.

Yes. The parser handles comma-separated links within a single header value. Simply paste the full Link header value including all links, and the tool will split them correctly, respecting angle brackets to avoid splitting URIs that contain commas. Each link is then individually parsed and displayed with its own URI, parameters, and validation results.

Yes, our Link Header Parser is 100% free to use with no signup required, no usage limits, and no hidden charges. Parse as many Link headers as you need - there are no restrictions on the number of headers or links you can inspect. No registration, no API keys, and no premium features.