JavaScript SEO Chrome Extension
Rendering Difference Engine
Identify SEO signals added, removed, or altered during JavaScript rendering — without digging into the code.
Add to Chrome for Free
Find critical differences in a click.
After years of JavaScript SEO audits, we created the tool we wished we had all along — and made it free.
The Rendering Difference Engine immediately highlights discrepancies between response HTML and rendered HTML for any page. It groups and reports findings based on the key SEO elements that impact how Google crawls, understands, and indexes URLs.
JS SEOs just found a new best friend.
An extension that unlocks faster audits, fuels accurate analysis, and translates into clear documentation for developers.
What does it check?
- Crawling & indexing signals
- Metadata
- Headings
- Internal links
- Page copy
- Images and media
How does it help?
- Streamlines JS SEO audits
- Free to use
- Instant, in-a-click report
- Only SEO-critical info
- Makes documenting easy
- Highlights right on the page
Comprehensive. Clear. Concise.
Everything you need to know as an SEO in an intuitive, at-a-glance interface.
Specifically focused on the on-page factors that impact SEO.
Cover all of your bases in just one click, including crucial crawling and indexing tags, page copy, media, and links.
Categorizes findings in SEO terms for easy analysis & documentation.
Find unique tabs for each SEO factor, showing exactly what changed in the rendered HTML specific to the element.
Highlights what matters, removes the fluff that doesn't.
The Rendering Difference Engine pulls out the discrepancies in clear callouts and lets you easily export the information.
10000/10 - really easy to visually see what's in or not in the HTML! Makes it a lot easier to communicate it to more junior members of the team and show them why client-side JS can be detrimental and is easier to show developers what you're talking about and why you're talking about it.
Emma Russell · Founder at Oxford Comma Digital
Want to easily troubleshoot CSR JS Reliance and Differences with raw HTML easily? There's a new Free Chrome Extension You can use! The Rendering Difference Engine by Gray Dot Company (aka, Tory Gray & team).
It segments and highlights the JS vs raw HTML differences in the headings, links, page copy, media and major configurations in an easy to visualize way.
This is more important than ever due to AI search platforms lacking JS rendering capabilities!
Aleyda Solís · Founder & International SEO Consultant — Orainti
What a great extension! I love that I can see the Javascript impact on the webpage, it helps me a lot with my and my clients' websites. What needs to be fixed is clear at a glance! And I'm not even a Tech SEO or Javascript expert. Can't even imagine the value they will get from this tool.
Alexander Hess · Founder, Mentor & Consultant — AH Design Academy
Frequently Asked Questions
Have a question that we didn’t answer? You can always contact us to get more info.
How are you rendering with this tool? (Is it Googlebot-rendered?)
Currently the tool shows browser-rendered content, but we have plans to create a version that identifies Googlebot-rendered content. Since there are fixed and usage costs when sourcing from Google, it will be a paid version with volume-based pricing tiers.
If you need that insight today, or you need it for an entire site, we recommend Sitebulb (with JS rendering turned on).
How does RDE determine what’s included in response and rendered HTML? How does it know what’s removed and/or added by JavaScript?
We’re using two well-known and accepted libraries to build these views of pre/post-browser rendering:
jsdiff - a library which allows the extension to generate differences between two texts for a character-by-character comparison.
js-beautify - this library formats the two sets of HTML into tables for “readable” line-by-line comparisons.
You can learn more about either library at the links above.
Can I view rendered HTML for mobile devices?
Yes! Change the user agent in your browser, then reload the extension to see mobile rendered HTML.
Does this extension collect my data?
To keep it short and sweet... no! But you can get the longer version of “no” by reading our still-really-short extension privacy policy.