
Ask HN: I want to build software on top of existing websites, where is the line? - askQuestion
It&#x27;s a tricky area as evidenced by cease &amp; desist letters from craig&#x27;s list among other things. For example, if I want to make something that helps people do some additional processing on the information already available to them is that okay?<p>Take CL&#x27;s TOU:<p>&quot;USE. You agree not to use or provide software (except for general purpose web browsers and email clients, or software expressly licensed by us) or services that interact or interoperate with CL, e.g. for downloading, uploading, posting, flagging, emailing, search, or mobile use. Robots, spiders, scripts, scrapers, crawlers, etc. are prohibited, as are misleading, unsolicited, unlawful, and&#x2F;or spam postings&#x2F;email. You agree not to collect users&#x27; personal and&#x2F;or contact information (&quot;PI&quot;).&quot;<p>Say I make an app that helps people organize the craigslist postings they are considering responding to. It sounds like my users would be users by violating the TOU.
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coreyp_1
I would advise you to be careful. It is always dangerous to build your
business on someone else's. It is very easy for them to pull the rug out from
under you!

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insoluble
Except when that business is in making plugins for popular software. At least,
many people seem to base their businesses on making plugins. In fact, even
making apps for a particular platform or operating system has this problem.
The real question to ask is the likelihood of that foundation being lost on
short notice. In this case, since the User Terms forbids building upon the
platform, to do so would clearly be a bad idea without getting specific
permission (possibly by offering a commission).

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chris_va
You can always contact the site owners and see what they are OK with. If you
are uncomfortable doing that, you should probably do something else.

