Is it legal to add content to a third party sites via a browser extension?


I want to create an extension that adds content on third party sites.
I will not show any advertising and I will not hide the site's content.

I'd like to add my related content to 5 or 6 third party websites, something like this Obviuosly, only my users, if they have installed my browser extension, will see my contents on third party websites.

Are there legal policy problems about the developing of this extension or could i proceed without any problem?

Can the site owner ban my extension or sue me?

Legal Website Terms And Conditions

asked Nov 30 '12 at 18:10
Giorgio Resci
8 points
Top digital marketing agency for SEO, content marketing, and PR: Demand Roll
  • Upvoted because everyone should be aware of a scam mentioned in my reply below. – Steve Jones 9 years ago
  • The question seems unclear. Could you show a fake example? – Billy Chan 9 years ago
  • Ok, something like this Resci 9 years ago

2 Answers


If people choose / authorize to install an extension that adds / augments content on specific sites, I don't see the problem with it. At a higher level Alexa, Google, AOL, Yahoo (and adblock for that matter) extensions all do this in some way.

How you get the user to install, how you choose to disclose what data is available and what you do with such data is typically where extension providers have problems with their users.

Of course, IANAL so if you want a true representation of what your exposure is, consult with your lawyer.

answered Dec 1 '12 at 01:36
Jim Galley
9,952 points
  • I tend to agree with your point but doubt the example. When you mention Google, did you mean Google cache to show sites' content? I think that's agreed by site owner by robots.txt and different from @Giorgio case. How about Diigo? This tool allow users leave marks and discussions on any site. Maybe Giorgio could check their terms. – Billy Chan 9 years ago
  • @BillyChan re: google - see . The toolbar provides additional info about the site (likes, optionally pagerank + links) & allows you share with G+ or whatever social net you like. Diigo is similar with the additional step to support screen capture & annotations. It also allows sharing ( through its private portal or other social nets. – Jim Galley 9 years ago
  • jimg, it seems there is misunderstanding. What you mentioned is a toolbar, while @Giorgio asked about content on website. The Diigo annotation may fit the case better. Chan 9 years ago
  • Sorry, I used as an example: a third party site with my content injected into it. I'd like to put content directly into the webpage's layout, not in a toolbar – Giorgio Resci 9 years ago
  • well - one could say that firefox is activated it injects content into the layout (for a very specific audience) and when adblock is activated it strips out specific content (ads). both "modify" public pages displayed to the user based on options set in the plugin / extensions. Its up to the plugin / extension provider to make such options visible to the user and to "do no harm" with such activity data (per Steve Jones concern). – Jim Galley 9 years ago


This is the attack vector used by a scam that attacks HSBC bank customers. The customers think they are "safe", as they have one of those hardware keys that changes code every few seconds. The bank think that the two-part authentication is sufficient. They all forget the browser is easily compromised. Locks don't matter if the thief is invited in.

No doubt the same trick applies to other banks too, not just HSBC.

I spoke to one of the bank's so-called security "experts" and they were so proud of rolling out these hardware key generators, until I pointed out that they made their customers a lot less secure, by giving a false sense of security.

answered Nov 30 '12 at 19:09
Steve Jones
3,239 points
  • Your answer is completely OT. – Giorgio Resci 9 years ago
  • OT = On Target? – Steve Jones 9 years ago
  • OT means Off Topic – Giorgio Resci 9 years ago

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