Preload / Prefetch Generator
Generate resource hint link tags for preload, prefetch, preconnect, dns-prefetch, and modulepreload with live validation.
About This Tool
The Preload / Prefetch Generator is a free browser-based tool that helps web developers create HTML <link> tags for resource hints — preload, prefetch, preconnect, dns-prefetch, and modulepreload. Instead of manually writing link tags and remembering which attributes each hint type requires, you configure resources through a simple form and get correctly formatted output instantly.
Resource hints are a critical part of modern web performance optimization. They tell the browser to start fetching resources or establishing connections before they are explicitly needed by the page. A well-placed <link rel="preload"> for your critical CSS or hero image can shave hundreds of milliseconds off your Largest Contentful Paint (LCP) score. Similarly, <link rel="preconnect"> to third-party origins like Google Fonts or analytics servers eliminates the DNS lookup, TCP handshake, and TLS negotiation latency.
This tool supports all five resource hint types defined by the W3C specification. For preload and modulepreload, you can specify the as attribute (script, style, font, image, fetch, document, audio, video, worker), the crossorigin attribute, a MIME type, media queries for responsive preloading, and the fetchpriority attribute for fine-grained priority control. The tool validates your configuration in real time, warning you about common mistakes such as forgetting the crossorigin attribute on font preloads or omitting the as attribute on preload tags.
Output is available in two formats: standard HTML <link> tags for pasting into your <head> section, and HTTP Link headers for server-side configuration (useful with CDNs and HTTP/2 server push). Built-in presets cover the most common scenarios — Google Fonts preconnect, CDN preconnect, critical CSS preload, hero image preload, and more.
Like every tool on DevToolbox, all processing happens entirely in your browser. No data is sent to any server. If you are working on SEO, you may also find our Meta Tag Generator helpful. For caching strategy, the Cache-Control Builder is a natural companion, and the Performance Budget Calculator can help you decide which resources to prioritize.
How to Use
- Click Add Resource or select a Common Preset to start. Presets like "Google Fonts Preconnect" or "Hero Image Preload" populate fields automatically.
- Enter the URL or origin for the resource. For preconnect and dns-prefetch, use the origin only (e.g.,
https://fonts.gstatic.com). For preload and prefetch, use the full resource path. - Select the Resource Hint type — preload, prefetch, preconnect, dns-prefetch, or modulepreload.
- Set the as attribute for preload and modulepreload (e.g., font, style, script, image). Review any warnings that appear below the resource.
- Configure crossorigin if the resource is cross-origin. Fonts always require
crossorigin="anonymous"even for same-origin requests. - Optionally set fetchpriority (high / low / auto), a MIME type, or a media query for responsive preloading.
- Toggle between HTML Tags and HTTP Header output formats. Click Copy (or press Ctrl+Shift+C) to copy the generated output to your clipboard.
FAQ
What is the difference between preload and prefetch?
Preload tells the browser to fetch a resource that is needed for the current page with high priority. The browser downloads it immediately. Prefetch hints that a resource will likely be needed for future navigations, so the browser downloads it with low priority during idle time. Use preload for critical resources on the current page (CSS, fonts, hero image) and prefetch for resources on the next page the user is likely to visit.
When should I use preconnect vs dns-prefetch?
Use preconnect when you know the browser will need to connect to a third-party origin soon. It performs DNS lookup, TCP handshake, and TLS negotiation in advance. Use dns-prefetch as a fallback or for origins that are less critical — it only performs the DNS lookup. A common pattern is to use both: <link rel="preconnect"> for modern browsers and <link rel="dns-prefetch"> as a fallback.
Why do preloaded fonts require the crossorigin attribute?
Fonts fetched via @font-face use CORS by default, even for same-origin requests. If you preload a font without the crossorigin attribute, the browser will fetch it twice — once from the preload (without CORS) and once from the @font-face rule (with CORS). Adding crossorigin="anonymous" ensures both requests match and the preloaded resource is used.
What is modulepreload?
modulepreload is a specialized resource hint for JavaScript ES modules. Unlike a regular preload with as="script", modulepreload not only fetches the module but also parses it and prepares it for execution. It also fetches the module's static dependencies. This makes it more efficient for modern JavaScript applications that use ES module syntax (import/export).
What does the fetchpriority attribute do?
The fetchpriority attribute (high, low, auto) gives the browser a hint about the relative priority of a resource fetch. Setting fetchpriority="high" on a hero image preload tells the browser to prioritize it over other images. Setting fetchpriority="low" on a less important preload can prevent it from competing with critical resources. The default is auto, which lets the browser decide.
Is my data safe?
Yes. All tag generation and validation happen entirely in your browser using client-side JavaScript. No URLs, resource configurations, or any other data is transmitted to any server. It is completely safe to use with internal URLs, staging environments, or any other sensitive configuration.
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