>Scraping against the TOS is super bad netizen stuff, and I dont think people should be posting positive reviews of people doing this. Breaking captchas and the like is basically blackhat work and should be looked down upon, not congratulated as I see in this thread.

Not really.

Scraping, in my opinion, isn't black hat unless you are actually affecting their service or stealing info.

If you are slamming the site with requests because of your scraping, yeah you need to knock it off. If you throttle your scraper in proportion to the size of their site, you aren't really harming them.

In regards to "stealing info", as long as you aren't taking info and selling it as your own (which it seems OP is indeed doing), that is just fine.

tl;dr: Scraping isn't bad / blackhat as long as you aren't affecting their service or business.

> If you throttle your scraper in proportion to the size of their site, you aren't really harming them.

And do you understand their site infrastructure to know whether you're doing harm? It's perfectly possible that your script somehow bypasses safeguards they had in place to deal with heavy usage, and now their database is locking unnecessarily.

Eh, this is pretty weak. Scrapers are no different from other browsing devices. The web speaks HTTP. There's no reason that using another HTTP browser would cause any disparate impact just by virtue of not being a conventional desktop browser -- you've thrown out a pretty absurd hypothetical. In fact, scrapers usually cause less impact because they usually don't download images or execute JavaScript.

I did an analysis and a session browsed with my specialized browser would always consume less than 100K of bandwidth (and often far less), whereas a session browsed with a conventional desktop browser would consume at least 1.2 MB, even if everything was cached, and sometimes up to 5 MB. In addition, on the desktop, a JavaScript heartbeat was sent back every few seconds, so all of that data was conserved too.

Because we were a specialized browser used by people looking for a very specific piece of data, we could employ caching mechanisms that meant that each person could get their request fulfilled without having to hit the data source's servers. We also had a regular pacing algorithm that meant our users were contacting the site way less than they would've been if they were using a conventional desktop browser.

Our service saved the data source a large amount of resource cost. When we were shut down, their site struggled for about two weeks to return to stability. I think they had anticipated the opposite effect.

Our service also saved our users a large amount of time. We were accessing publicly-available factual data that was not copyrightable (but only available from this one source's site). There's no reason that the user should be able to choose between Firefox and Chrome but not a task-specialized browser.

It is true that some people will (usually accidentally) cause a DDoS with scrapers because the target site is not properly configured, but the same thing could be done with desktop browsers. It doesn't mean that scrapers should be disadvantaged.

A small counterpoint to this -- in the airline industry, it's relatively commonplace for seat reservations to be made for a user _before_ payment has occurred. In this case, if you're mirroring normal browser activity, you can (temporarily) reduce availability on a flight, potentially even bumping up the price for other, legitimate users, and almost certainly causing the airline to incur costs beyond normal bandwidth and server costs. I'm sure there are many other domains for which this is also the case, however rare.

If they don't do the seat reservation behind a POST, or at least blacklist the reservation page in robots.txt, I have no sympathy.

I've had this happen regularly enough that I developed the habit of finding a fare in the morning and then returning at 11pm ready to buy.

Cinemas and some online shops do the same. I've always wondered if it's possible to block any tickets sales for entire flights/screenings/products this way.

And if airline tickets are based on supply v demand, it might even be possible to drive down ticket prices by suddenly dropping a load of blocks near to the flight date.

If you have ever tried to buy hot tickets online and not been able to get any, this is due to bots. Bots are the scalpers friend.

This can easily be prevented by requiring ID matching the ticket on entry, but the ticket sellers often don't seem to care.

> you've thrown out a pretty absurd hypothetical

Not even remotely absurd. Where is the data your scraper consuming coming from? It's almost always served from some sort of data repository (SQL or otherwise). That data costs far more per MB to serve up quickly than JS/CSS/images.

Suppose, for example, you host a blogging platform that has one very popular user. Most accounts on your site don't get a ton of visitors, and that one very popular user's post are all stored in cache.

Then along comes a scraper. He thinks, "Hey, this site is serving up a million page impressions a day. It can definitely handle me scraping the site".

But when he runs the scraper, he fills up the cache with a ton of data that it doesn't need, causing cache evictions and general performance degradation for everyone else.

There are already 6-8 major scrapers that do this constantly, across the whole internet, called search engines. You can't handle that?

What if you get a normal user who says "Hey, I wanna see some of the lesser known authors on this platform" and opens up a hundred tabs with rarely-read blogs? What if you get 10 users who decide to do that on the same day? Is it reasonable to sue them? Should there be a legal protection to punish them for making your site slow?

Don't blame the user for your scaling issues. If the optimized browser ("scraper") isn't hammering your site at a massively unnatural interval, it's clean. And if it is, you should have server-side controls that prevent one client from asking for too much data.

These are just normal problems that are part of being on the web. It's not fair to pin it on non-malicious users, even if they're not using a conventional desktop browser.

Search engines respect robots.txt – not sure many scrapers do.

First, search engines are scrapers. No need to make a distinction.

Second, search engines don't always respect robots.txt. They sometimes do. Even Google itself says it may still contact a page that has disallowed it. [0]

Third, robots.txt is just a convention. There's no reason to assume it has any binding authority. Users should be able to access public HTTP resources with any non-disruptive HTTP client, regardless of the end server's opinion.

[0] "You should not use robots.txt as a means to hide your web pages from Google Search results. This is because other pages might point to your page, and your page could get indexed that way, avoiding the robots.txt file." / http://archive.is/A5zh8

In the Google quote you link to, Google is not contacting your page. Rather, Google will index pages that are only linked to, which it has never crawled, and will serve up those pages if the link text matches your query. That's how you get those search results where the snippet is "A description of this page has been blocked by robots.txt" or similar.

There's a somewhat related issue where to ensure your site never exists in Google, you actually need to allow it to be crawled, because the standard for that is a "<meta name=noindex ...>" tag, and in order to see the meta noindex, the search engine has to fetch the page.

And the original point of my comment was that doing this is extremely rude and not appropriate, not that it couldn't be done or that others weren't doing it.

Feel free to send any request to any server you want, it is certainly up to them to decide whether or not to serve it, but that doesnt absolve you of guilt from scraping someone's site when they explicitly ask you not to.

Please don't conflate "extremely rude", "not appropriate", and "guilt". Two of these are subjective opinions about what constitutes good citizenship. The last one is a legal determination that has the potential to deprive an individual of both his money and liberty. We're discussing whether these behaviors should be legal, not whether they are necessarily polite.

I never did.

You are posting in a comment thread underneath my reply about rudeness and impoliteness, ironically being somewhat rude telling me off about what not to conflate when it was never what I said.

Google will put forbidden pages in its index. It doesn't scrape them. (The URL to the page exists even without visiting the page.)

We do, and we also use our own user-agent string: "SiteTruth.com site rating system". A growing number of sites reject connections based on USER-AGENT string. Try "redfin.com", for example. (We list those as "blocked"). Some sites won't let us read the "robots.txt" file. In some cases, the site's USER-AGENT test forbids things the "robots.txt" allows.

Another issue is finding the site's preferred home page. We look at "example.com" and "www.example.com", both with HTTP and HTTPS, trying to find the entry point. This just looks for redirects; it doesn't even read the content. Some sites have redirects from one of those four options to another one. In some cases, the less favored entry point has a "disallow all" robots.txt file. In some cases, the robots.txt file itself is redirected. This is like having doors with various combinations of "Keep Out" and "Please use other door" signs. In that phase, we ignore "robots.txt" but don't read any content beyond the HTTP header.

Some sites treat the four reads to find the home page as a denial of service attack and refuse connections for about a minute.

Then there's Wix. Wix sometimes serves a completely different page if it thinks you're a bot.

> I did an analysis and a session browsed with my specialized browser would always consume less than 100K of bandwidth (and often far less), whereas a session browsed with a conventional desktop browser would consume at least 1.2 MB, even if everything was cached, and sometimes up to 5 MB. In addition, on the desktop, a JavaScript heartbeat was sent back every few seconds, so all of that data was saved too.

Bandwidth is certainly part of it, but there's also also database and app-server load (which may be the actual bottleneck) that a scraper isn't necessarily bypassing.

Yeah, I just have a hard time buying that a scraper that does less than a conventional desktop browser is going to accidentally stumble across something that causes the server-side to flip out. I'm not really sure in what case your hypothetical is plausible.

Scrapers are usually used to get publicly-available data more efficiently. What you're describing would basically require the scraper to hammer an invisible endpoint somewhere, but there's no reason the scraper would do that -- it just wants to get the data displayed by the site in a more efficient manner. I suppose the browser could enforce a cooldown on an expensive callback via JavaScript, which a scraper would circumvent, but IMO that's not a fair reason to say scrapers are disallowed; cooldowns should be enforced server-side. There's no way to ensure that a user is going to execute your script. That's just part of the deal.

Everything about scrapers means less server load; no images, no wandering around the site trying to find the right place, no heavy JavaScript callbacks that invoke server-side application load, etc. Scrapers are just highly-optimized browsing devices targeting specific pieces of data; it's logical that they would be cheaper to serve than a desktop user who's concerned about aesthetics and the like.

In our specific case, those JavaScripts we didn't download included instructions to make over 100 AJAX requests on every page load. No wonder users were looking for something more efficient.

So I agree that a scraper isn't necessarily bypassing some load-heavy operations, but I find it highly implausible that a non-malicious scraper would be invoking operations that cause extra load (beyond just hitting the site too often). Frankly, I'd be surprised if there was a functional scraper that regularly invoked more resource cost per-session than a typical desktop browsing session to get equivalent data.

> What you're describing would basically require the scraper to hammer an invisible endpoint somewhere

That wasn't my point. My point was: a lot of a website's costs are hidden from a web scraper (e.g. database load), so a scraper can't claim, based on the variables they can observe (bandwidth), that they're costing the website less than normal traffic.

I was basically responding to statements like this:

> In fact, scrapers usually cause less impact because they usually don't download images or execute JavaScript.

There's really no way for a scraper to know that unless the website tells them. Their usage pattern is different than typical users and raw bandwidth (for stuff like static images) may not matter to the website.

It's true that there's no way to know that for sure, but it doesn't make sense that a scraper, by virtue of its being a scraper, is incurring additional load. A scraper is only making requests that a person with a desktop browser or any other appliance that speaks HTTP could make. What's the difference between a user clicking the same button on the page 50 times or holding down F5 and a scraper that pings a page once a minute?

Your argument is basically boiling down to "scrapers could hit one load-heavy endpoint too fast", but so could desktop browsers. So I don't see what it has to do with scraping.

> but it doesn't make sense that a scraper, by virtue of its being a scraper, is incurring additional load

It does, because scrapers don't have normal usage patterns. They're robots and behave like robots.

> What's the difference between a user clicking the same button on the page 50 times or holding down F5 and a scraper that pings a page once a minute?

Typical users aren't usually in the habit of mashing F5, especially not for robotically long periods of time. It's basically the difference between a theoretical activity and an actual activity.

Basically, scraping is not regular usage, and I don't think it's correct to pretend that they're equivalent (or more extremely, that scraping is less costly to the website).

Scrapers are usually coded to have as regular of a usage pattern as possible, so that the data they retrieve is as much like the data the end user would receive as possible.

For example, Googlebot does everything in its power to ensure that it sees pages the same way that end users sees them, executing JavaScript and performing OCR to try to read information conveyed in images. Google also has non-Googlebot scans to try to determine if a page is serving different content to Googlebot-labeled scans, and they penalize sites that they suspect of doing this.

While it is true that someone could write a scraper that obviously behaved robotically, it is also true that someone could use their desktop browser in a robotic way. Mashing F5 is so common that there are many ancient memes referring to and making jokes about that activity. There are extensions that end users use to record browser macros, behaviors they want their browser to repeat over and over again.

However, this conversation about whether scrapers behave robotically or not is moot because a web site shouldn't break down under load when someone uses it in a slightly-irregular way. The obvious, crappy scrapers are trivial to block. The ones that blend into the traffic are no harm, no foul. If you can't tell the difference between an optimized browser like a scraper and a general-purpose browser like Chrome, why shouldn't it be allowed to talk to your site?

> Typical users aren't usually in the habit of mashing F5, especially not for robotically long periods of time. It's basically the difference between a theoretical activity and an actual activity.

Just like every university site ever is completely down during signup days because everyone is mashing F5.

Link me your site, I’ll treat it like a college student waiting to be able to sign up for their classes.

Have run into exactly this before. Wrote a scraper that retrieved results from a trivia league website. Tried to be a polite scraper (<1 request per second) but the site still crashed - even with 5 seconds of sleep between requests. They were doing something weird with DB connection management (maybe just forgetting to close it and letting it timeout? I remember figuring it out but it's been quite a while) and so after N very reasonably spaced queries the site would reproducibly start throwing an uncaught MAX_DB_CONNECTIONS_EXCEEDED and just be down for everybody everywhere who might've wanted to use it.

It seems like you could easily hit those scaling issues by manually browsing the website. While I agree that it sucks to take down a site by scraping, in that specific case it sounds like the performance issues are their fault and not yours. That said, once I realized the effect my scraping had, I would (hopefully) cease my scraping.

So the thing is, I could totally believe they never saw this traffic pattern under normal load. I'd expect bar trivia scores in a certain mid-sized US city are one of those niche things where you have a very low number of uniques but each unique then pokes around on 9 or 10 pages while they're there. The fact that the site didn't crash during normal browsing was what originally led me to speculate they were maintaining an open DB connection per session. If that was indeed the issue, I could totally imagine they'd only rarely (never?) had 100+ "concurrent..ish" unique visitors.

Ok, then why couldn't you revise your scraper so that it did everything in a single session, to avoid this problem?

To me, for private, personal use, a scraper should emulate a normal human browser as much as possible to avoid causing site problems and to avoid detection. If what you're doing can be done in the background, or by a cron process at some odd hour, it doesn't have to be fast at all, and you can set the timings to be similar to a normal human.

Now that I think about it a bit more, I think my hypothesis was that DB connections were allocated at the session level and that without cookies enabled each request initiated a new session.

I'd consider that a bug not a feature but I still think it's incumbent on me, the guy scraping the website, not to trigger it.

That is a classic connection pooling/lifecycle bug, and usually one that gets caught in the first few days of having multiple people utilizing a product/service, worst case.

If someone's production site, thats been around for while, had a bug like this that can be caused by what you describe, I'd love to see how many real users they have. I'm sure its possible under certain circumstances, but its definitely bad engineering that would be caused by literally any traffic.

You can avoid triggering this in your scraper by activating a cookie jar. Pretty simple most of the time. Even commandline cURL and wget support it. I'm sure you figured that out already, but just for anyone who's wondering. ;)

That said, while obviously you want to avoid triggering the bug since it offlines your data source, this is definitely in the site's court to fix and could easily be triggered by normal usage. Some people browse with cookies disabled, especially since the EU passed its "cookie law", requiring sites to get consent before storing a cookie on visitors' machines. If you've started to notice more sites talking about cookies over the last year, that's why. [0]

[0] http://ec.europa.eu/ipg/basics/legal/cookies/index_en.htm

>Now that I think about it a bit more, I think my hypothesis was that DB connections were allocated at the session level and that without cookies enabled each request initiated a new session.

Could also be something like storing hibernates second level cache in session. Unfortunately I've seen this, a significant chunk of the database was being copied into each users session.

I mostly agree with the post's author on the "I'm just automating something I'd otherwise be doing manually". If the local weather service publishes, say, barometric charts on their site - but has a TOS that prohibits me from scraping, and my alternative was to just hit their site every day and right-click and save-as on the chart - I feel absolutely no compunction in automating that. You need to be careful of the slippery slope though, when it's easy to grab every day's local barometric chart, it become too easy to think "Hey, I just need to stick that in a loop and I can grab 1000 different charts every day!". I'd personally _not_ do that. If it's something I'm likely to do "by hand" but would occasionally miss a day or three, I'll automate it no matter what the TOS says.

You're saying the site should pay him a consulting fee for the free load-testing service he provides?

One fair baseline is whether or not the custom User Agent you're using to scrape has request timing that's on the order of what a fast human visitor might do. If the site can't handle that, it's certainly not the UA's fault.

> Scraping, in my opinion, isn't black hat unless you are ... stealing info.

And as a webmaster, how can I tell the difference before it's too late?

> tl;dr: Scraping isn't bad / blackhat as long as you aren't affecting their service or business.

Analyzing data that you're not allowed to access gives you/your company a competitive advantage, which is affecting their service/business even if it's not posted/distributed publically.

I don't follow your argument. How does one get their scraper access to data they would otherwise not be able to access through 'normal' browsing techniques?

Example I know of: You can scrape your competitor's Facebook pages since their creation and output nice graphs of which posts generated what kind of likes and suscriptions. This data is usually limited to the owner of the page.

But I can get the same data with manual browsing. And I can just as well pay some chinese to collect the data and input it in my database.

Automated scraping is just a way to drastically reduce labor costs for information collection. Sure, it's a competitive advantage, but I think disallowing it or calling it unethical is a pretty big can of worms. Why is it ok if something is done by humans but not ok if a computer does it by himself?

If someone was to sit down and use paper + pencil + time to accomplish the same thing, would you still have issue with it? It's publicly available data. Should you also not watch your competitors television ads or walk in to their physical store and browse around?

The difference being that I can scrape the data of ALL my competitors since 2008, get the number of likes and comments of every single comment and automatically generate graphs of the data. Thousands of man hours in one minute.

This gives an unfair advantage to the tech-savvy "hackers". Facebook terms protects against this. Thus scraping it is disallowed.

I couldn't say if it would be moral or immoral to do this. Personally, I'm more concerned about the well being of poor scraper program that has to scrape through an entire decade of Facebook posts. Poor thing.

This is called hustling. I love it. What's not to like?

By ignoring robots.txt and bypassing capchas.

'Bad netizen stuff'? Is this a comment from 1997? Breaking captchas is 'blackhat'? What cozy hippy internet alternative reality does this come from?

These are the same websites and companies that are loading evercookies and doing browser fingerprinting, that break as much as possible the anonymity citizens should enjoy, with Real Name policies, using network analysis to find who your friends are and what your politics and buying habbits are, that routinely rip private information from you cell phone and share it with oppressive regimes.

You're not in Kansas anymore Toto.

> misuse of other's resources against their will

Nonsense, there is no implication that this activity is illicit. Many sites (I have worked with hundreds) are happy to be included in my service, but don't have the technical ability to provide a data feed. They were delighted when I told them I could aggregate their content without any extra work on their part.

We respect TOS, we respect robots.txt and so on. Just because you study scraping techniques doesn't mean you intend to break the law.

> Breaking captchas and the like is basically blackhat work

Um, captchas only work if they work. If breaking them is trivial, they shouldn't exist. Don't shoot the messenger for pointing out the front door is unlocked.

"Don't shoot the messenger for pointing out the lock on your door can be picked"

"Don't shoot the messenger for pointing out that robots are capable of opening doors."

Sometimes, scraping a website is the only way at your disposal to fetch relevant information, you've paid for (or not). It could be simply the opening schedule of your local administration or the status of different pieces of public infrastructure.

If your administration don't have the resources (and it's often the case) to maintain a proper JSON API for you to fetch with a fancy python lib, then, it's not "super bad netizen stuff" to scrap a few HTML/PDF/XLS, parse them and display them for convenient public consumption on your personal website (and paying for the bandwidth).

It's 2016. State-companies holding a third party responsible for their own outages and poor planning is _bad faith_[1]. ETL? Never heard of it?

[1]: https://citymapper.com/i/1208/soutenez-citymapper-et-lopen-d... (french)

To know the TOS of a page, you need to read it. To know which links are part of a site and which are not, you need to follow the link. Having a TOS as part of the page content is akin to having a sign in a room, only readable by entering the room, that says "you are not allowed to enter this room".

Yes, this defense is being petty abotu details, but I find businesses using post-hoc discoverable limitations to limit people rights annoying.

Instagram or Facebook, they thrive on stolen or relinked content and monetize it day in day out.

Being amazed at this kind of bad behaviour where the targets are some of the most despicable companies on the web is a bit ironic. Scrape away, these companies hurt the web, let's hurt them (even though, all the scraping in the world won't have any impact).

So its moral to continue bad behavior because someone else did it?

It's not bad behavior. The companies that profit off this try to make you think it's bad behavior because they don't want to risk your taking any profit away, and they've installed laws that let them get away with this. They can violate to their heart's content, but unless someone else in the oligopoly sues over the matter (which they would never do, because the precedent may prevent their abuse of the law), the peons will be forced to comply. That's not how a competitive marketplace works, and it's why we have such a hard time breaking gridlock on web properties.

> This post is kind of crazy, aggrandizing bad behavior and misuse of other's resources against their will.

How so? I send a web request, they send me the content in a response. If they aren't happy with that then they should refuse my request.

I disagree. DOSing a site is bad behaviour, regardless of how you do this. But accessing it in an automated way instead of a browser? Not really. The deal on the Internet is like this: a website owner can provide whatever they want, and a visitor can read it however they want. Discriminating visitors based on whether or not they seem to be bots instead of people is going beyond what the site provider should do. So is detecting and blocking people using adblockers.

I agree with your assertion about "the deal on the Internet", but I disagree with your conclusions. IMO, site owners should be able to discriminate all they want. However, when someone's browser (or other software...) makes a request to that site, and the site serves them some data, the user should be able to do with that what they will: either honor or decline the requests for them to download various ads or JavaScript, for instance. It should be up to the site owner to craft their site to follow their policies and whims. What I'm completely against is the idea of using the government and law enforcement to enforce some site owner's policies. The only exception I can see for this is extreme cases where this general principle falls down: DOS attacks, for instance.

If I can modify my web browser to view a site, but skip the ads, that should be my right. If the site owner codes their site to detect this and then blocks my request to see their site, that should be their right. If I modify my ad-blocker to get around their ad-blocker-block, that should be my right, and so on. As long as we don't get into something like DDOS territory where a reasonable web site has no good technological way of avoiding the problem caused by a user, this isn't something for government to get involved in.

Hmm... yeah, I guess what you (and the other commenter) describe is fairer than what I wrote. Thanks!

IMO all's fair as long as the solution is technical. Dragging it into the courts because you can't figure out how to stop them technically (especially if they're not actually disrupting anything) is inappropriate.

We need updated legislation that covers malicious actors that issue DDoS attacks but leaves normal people that scrape consciously and carefully alone.

So you think that people should waste their time solving captcha are the solution? people are paid to solve captcha, there's always something like that and then the users suffer more. It's not a solution at all.