Free Subresource Integrity (SRI) Hash Generator
A Subresource Integrity (SRI) generator computes cryptographic Base64-encoded hashes (such as `sha384-...`) of remote CDN JavaScript files or CSS stylesheets, producing HTML `integrity` attributes that prevent browsers from executing tampered or hijacked third-party code.
Paste script URL or code content into ScanSuite's SRI generator, select target algorithms (`sha384` or `sha512`), and copy the generated `integrity="sha384-..."` HTML `<script>` or `<link>` snippet directly into your web pages.
Introduction to Subresource Integrity (SRI)
Modern web applications rely heavily on Content Delivery Networks (CDNs) to serve third-party JavaScript libraries and CSS frameworks like Bootstrap, jQuery, and React. However, if a CDN provider is compromised or a supply chain attack occurs, malicious actors can inject web shells or keyloggers into those shared files.
Subresource Integrity (SRI) is a W3C security specification that allows browsers to verify that files fetched from third-party CDNs match expected cryptographic digests. ScanSuite's free SRI hash generator calculates Base64-encoded `sha256`, `sha384`, and `sha512` digests, generating ready-to-paste HTML tags in seconds for production deployment.
What Is Subresource Integrity (SRI)?
SRI adds an `integrity` attribute containing a cryptographic hash to `<script>` and `<link>` elements (for example, `integrity="sha384-d65gh..."`). Before executing a script or applying a stylesheet, the browser computes its local hash of the received bytes.
If the computed hash matches the `integrity` string, the browser executes the file; if the hashes differ (indicating file tampering or incomplete transfer), the browser blocks execution and logs a CORS/SRI security error to the developer console.
SRI is a defense-in-depth control recommended by OWASP and Mozilla Developer Network for any third-party script loaded from external CDNs.
Why Use an Online SRI Generator?
Generating SRI hashes manually requires running command-line pipelines like `openssl dgst -sha384 -binary file.js | openssl base64 -A` across every vendor update.
ScanSuite's online SRI generator automates hash creation for both file uploads and remote CDN URLs. It verifies Cross-Origin Resource Sharing (CORS) headers and outputs clean `<script src="..." integrity="..." crossorigin="anonymous">` tags instantly.
Automated HTML snippet output reduces copy-paste errors that leave out the required `crossorigin="anonymous"` attribute and break integrity validation in production.
Who Uses SRI Generators?
Frontend developers use SRI generators when referencing external CDN scripts to satisfy security compliance audits.
Security engineers implement SRI attributes across production web builds to mitigate supply chain and CDN compromise vectors.
DevOps and CI/CD engineers automate SRI hash generation during web artifact build pipelines.
How Subresource Integrity Verification Works
SRI hashes consist of the algorithm prefix (`sha256`, `sha384`, or `sha512`), a hyphen `-`, and the Base64-encoded raw binary hash of the target file bytes (e.g. `sha384-oqVuAfXR...`).
Because SRI operates across origins, external CDN servers MUST return `Access-Control-Allow-Origin: *` headers, and HTML tags MUST include `crossorigin="anonymous"` for browser verification to succeed.
Browsers compute the digest of fetched bytes using the same algorithm specified in the integrity attribute and reject mismatches before script execution begins.
SRI HTML Tag Example
Target Script: `https://code.jquery.com/jquery-3.7.1.min.js`
Generated HTML Tag:
`<script src="https://code.jquery.com/jquery-3.7.1.min.js" integrity="sha256-/JqT3SQfawRcv/BIHPThkBvs0OEvtFFmqPF/lYI/Cxo=" crossorigin="anonymous"></script>`
SRI Hash Algorithm Comparison
| Algorithm | W3C Recommendation | Digest Length | Best Use Case | |
|---|---|---|---|---|
| sha256 | Supported | 44 Base64 chars | Baseline integrity checking | |
| sha384 | Recommended | 64 Base64 chars | Industry standard for CDN script tags | |
| sha512 | Supported | 88 Base64 chars | Maximum security for sensitive applications |
Why Is My Script Blocked by SRI in Chrome or Firefox?
Verify that the CDN server returns an `Access-Control-Allow-Origin: *` header, and ensure your HTML tag includes `crossorigin="anonymous"`.
Related tools
- Hash Identifier — Identify unknown hashes
- Hash Generator — Generate MD5, SHA hashes
- Hash Generator — Calculate standard cryptographic hashes.
- CSP Generator — Build Content Security Policy headers.
- Security Headers — Generate secure HTTP response headers.
- Encoder Decoder — Encode strings into Base64.
- Robots.txt Generator — Configure web crawling rules.
Frequently Asked Questions
How do I generate an SRI hash?
Enter the URL of a script or stylesheet, or upload the file. The tool computes a SHA-384 (or SHA-256/512) hash with Web Crypto and gives you a ready-made `integrity="sha384-…"` attribute with `crossorigin="anonymous".
What is Subresource Integrity?
SRI lets the browser check that a file from a CDN has not been changed. If the file's hash does not match the `integrity` attribute, the browser refuses to load it.
Which hash algorithm should I use for SRI?
SHA-384 is the common default. SHA-256 and SHA-512 are also supported by browsers. MD5 and SHA-1 are not allowed.
Why is my SRI check failing?
The file has changed (a new version or minification), the CDN serves different content, or the `crossorigin` attribute or CORS headers are missing. Regenerate the hash for the exact file URL you load.
What is Subresource Integrity (SRI)?
A W3C security feature that enables browsers to verify that files fetched from CDNs have not been tampered with.
Which algorithm is recommended for SRI?
W3C recommends SHA-384 (`sha384`) as the optimal balance of speed and security strength.
Why is crossorigin="anonymous" required for SRI?
CORS is required so browsers can inspect the cross-origin file bytes to compute the verification hash.
What happens if an SRI hash check fails?
The browser blocks execution of the script or stylesheet and logs a security error in the console.
Does SRI affect website loading speed?
No. Hashing takes less than a millisecond in browser memory during file parsing.
Can I use SRI for internal local scripts?
SRI is intended for third-party cross-origin scripts, but can be used locally for build validation.
Are my file contents saved on ScanSuite servers?
No. File hashing is performed client-side using browser Web Crypto APIs.
What is the format of an SRI attribute?
Formatted as `integrity="[algorithm]-[base64-hash]"` (e.g. `integrity="sha384-abc..."`).
Can I specify multiple SRI hashes in one tag?
Yes, separate multiple hashes with spaces inside the `integrity` attribute.
What happens if a CDN updates a script file without changing the URL?
The SRI check will fail because file bytes changed; you must update the SRI attribute whenever script contents change.
Can SRI protect against supply chain attacks?
Yes, it prevents malicious script replacements on third-party CDNs from executing in your visitors' browsers.
What is the difference between CSP and SRI?
CSP controls WHERE resources can be loaded from; SRI verifies WHAT content those resources contain.
Is SRI supported by all modern web browsers?
Yes, SRI is supported across Chrome, Firefox, Safari, Edge, and mobile browsers.
Is this SRI generator tool free?
Yes, ScanSuite provides free unlimited SRI hash generation without registration.
Can I generate SRI hashes for CSS stylesheets?
Yes, SRI works for both `<script>` and `<link rel="stylesheet">` tags.
How do I generate SRI hashes in OpenSSL CLI?
Run `openssl dgst -sha384 -binary file.js | openssl base64 -A`.
What does the Base64 output ending in = mean?
Standard Base64 padding characters ensuring binary alignment.
Summary
ScanSuite's free SRI hash generator calculates Base64 sha256, sha384, and sha512 Subresource Integrity attributes for CDN script and stylesheet tags, protecting websites against supply-chain attacks.