top of page
  • Writer's pictureBrent Payne

Ensuring Web Security with Subresource Integrity: A Must for Every DeveloperIntroduction

In the vast expanse of the internet, where the speed of content delivery is as crucial as its accuracy, Subresource Integrity (SRI) stands as a guardian. Imagine it as a bouncer at the door of your website, ensuring that every script and stylesheet delivered to your visitors is exactly what it's supposed to be, free from any malicious tampering. For developers and website owners, understanding and implementing SRI is not just beneficial; it's a necessity.

Why Subresource Integrity Matters

The convenience of using Content Delivery Networks (CDNs) to host website resources comes with its share of risks. The primary danger lies in the potential compromise of these resources. A single breach can turn a helpful CDN into a conduit for malicious attacks, affecting countless websites and users. Here's where SRI comes into play, acting as a failsafe that verifies the integrity of the resources being fetched. By matching the resources against a known cryptographic hash, SRI ensures that they haven't been altered, keeping both the website and its users safe from harm.

Implementing Subresource Integrity

Implementing SRI is like giving your website a security upgrade. It involves specifying a base64-encoded cryptographic hash for each external script or stylesheet your site fetches. This hash acts as a fingerprint, unique to the unaltered version of the resource. If the fetched resource doesn't match the specified hash, the browser will block its execution, effectively preventing any tampered content from harming your site or your users.

Tools for Generating SRI Hashes

Generating the cryptographic hashes required for SRI may sound daunting, but it's quite straightforward with the right tools. Online tools like SRI Hash Generator provide a user-friendly interface for generating hashes. For those who prefer the command line, OpenSSL and shasum commands offer flexibility and efficiency. Regardless of the method, generating and implementing these hashes is a critical step in securing your web resources.

Cross-Origin Resource Sharing (CORS) and SRI

Combining SRI with Cross-Origin Resource Sharing (CORS) settings amplifies your website's security. This combination ensures that not only are the resources fetched without tampering, but they are also retrieved from sources that explicitly allow sharing. By setting the appropriate Access-Control-Allow-Origin headers, you maintain control over who can fetch your resources, adding an additional layer of security.


In the digital age, where security threats lurk around every corner, Subresource Integrity serves as a vital defense mechanism for your website. By ensuring that the resources your site utilizes are delivered without unexpected manipulation, SRI protects both your website's integrity and the trust of your users. For web developers and site owners, integrating SRI into your security strategy is not just a recommendation; it's a cornerstone of responsible web development.

Stay Safe, Stay Secure

Remember, in the world of web development, security is not a one-time setup but a continuous process. Staying informed, understanding the tools at your disposal, and implementing features like Subresource Integrity are fundamental to safeguarding your online presence. Let's build a safer internet, one website at a time.


Recent Posts

See All

ClubReq Gets A Link (Because They Asked)

I am a mentor for Techstars and have been for over 10 years. In those ten years I have mentioned to startups to ask ANYONE and everyone that they meet to link to their site. Yet, in all those times on


bottom of page