Let me start from an example to explain what is a non-directly accessible page.
After fully loading this post, you should see a charming picture below. If you share URL address of this post to your friend, he(she) should be able to see the same picture by clicking the shared link. So this picture is directly accessible.
Next, if you click the MORE button below it, you should see a secret version of the same picture. However, as far as I know there is no way to let your friend see the secret version by simply clicking a shared link. If you can make it, let me know and I will give you $1000.
So the secret version is something non-directly accessible. To see it your friend has to visit this post and click the MORE button.
If you use other change-detection services to monitor this post, you will not likely get alerted even if the secret version changes, because there is no input field to tell them to click the button before making comparison. However, with deep-watch you can explicitly make such request, just say “alert me when the picture that shows up after clicking MORE button changes ”.
In general, (whether intentionally or not) there are many ways to make web page contents not directly accessible with a shared URL. Here are some examples.
- Password protection
Site may ask user to login before showing any contents. This is the most commonly encountered scenario.
- CAPTCHA test
Site may ask user to recognize a distorted picture, or solve a puzzle, just to prove himself to be human but not robot. If user fails to provide correct answer, site won’t show anything.
- Session control
Site may ask user to visit page A before going to page B. In such case user can’t directly access page B by its URL.
- POST method
Some pages only show up after user submits a POST request. On the other hand，when user clicks a link or pastes URL in address bar, GET method is always the only option. If you are curious, see this page for the difference between those two methods.
- Programmatic rendering
Page may dynamically change its contents according to user inputs. Some contents do not show up without user interaction. This post is a fair example to demo such scenario.
Again, as far as I know, no other change-monitoring services, whether free or not, can handle above cases well. However, deep-watch works perfectly in all of them. It can interact with the page in the same way as human does, and retrieve the deepest page for you. Besides, we can do even more. Don't hesitate to have a try if you find other services can’t provide what you wanted. You will get more than expected 
P.S.
About the sample picture.
The lady in the picture names Lena Söderberg. This picture is a standard test image widely used in the field of image processing. It is very famous in computer science history. So I am not trying to promote nudity, just to let more people know the tricky part of science. See this page for more stories behind it.
About the $1000 betting
This is a serious campaign, so let's clarify all clauses before you start to work.
- The URL should point to a page hosted by deep watch
i.e. It should start with https://www.deep-watch.net/
- Your solution should be reproducible by average user in an out-of-box computer.
For example, the following methods are not acceptable.- Build your own browser and unconditionally show the secret picture when visiting deep-watch
- Configure your device to redirect deep-watch to some other server
- Inject your own code in your data link
- You should not hack deep-watch or related facilities.
For example, the following methods are not acceptable.- Inject malicious code on any page of deep-watch
- Take ownership of administrator account and modify deep-watch source code
- Take ownership of deep-watch’s domain or DNS server
- Take ownership of google’s server
- The $1000 will only be paid to the 1st who works it out.
We will announce on this page when the winner shows up.
- You need have a Paypal account to receive the money.
- We reserve the right to terminate the campaign at any time without prior notice.
If you work it out. Leave a message here and we will contact you.