Frequently Asked Questions

To see what the current status of Follow That Page is, see

User FAQ

Why would I use Follow That Page?

Follow That Page monitors web pages and notifies you via email when a page has changed. If you’re still not convinced, then read this message from a happy user:
I KISS YOU! I foolishly missed out on buying some Glastonbury tickets. It's a big music festival in the UK that sells out within 24 hours. Knowing that they sometimes make a tiny amount available, I had Follow That Page look at the ticket site. Today, a month after they first went on sale, my phone beeped at me. The page had changed. SOLD OUT had changed to CLICK HERE. I ran to the nearest internet connection and bought my ticket. An hour later they were all sold out again. THANK YOU! The internet is great because of people like you.
And in case you’re wondering: Follow That Page does not send SMS, but you can use a smartphone or an email-to-SMS service.

How does it work?

You enter the address of the page you want to follow, and your email address. Then on the next page you may provide some more information and create an account. From then, Follow That Page will send you regular emails with the added and/or removed text.

How often does Follow That Page check pages?

Per user, it can do 20 daily checks and 1 hourly check. You can enter any number of pages you like, but after checking 20 pages (in the daily run) it will stop and leave the rest for the next day. So, if you entered more than 20 pages, it will check all pages you entered, but it will take more than one day to do it. The same for hourly pages: if you set 5 pages to hourly checking, it will take 5 hours to check all of them, because it does only one check per hour. If you update to a Pro account, you’ll have 1000 daily checks, 20 hourly checks, 5 10-minute checks and 100 weekly checks. Click “Your account” in the menu to see the details. The daily run starts at 8:00 AM Central European time. When you enter a new page, it will be checked within a few minutes for the first time.

What happens when a page has changed?

Follow That Page will send a report of the changes to your email address. You can see an example here.

How does the filter work?

With filters, you can tell our robot which parts of a page are not interesting to you. Weblogs, for instance, often contain phrases like “five comments”, and every time it changes, you will get a report that is not very useful. With the line filter, it is easy to ignore certain lines. You just give a keyword or key-phrase (like “comments”), and every line that contains that keyword is ignored. You can also reverse the filter: if you only want to know when the price of an article changes, use keyword “price” and select “Ignore lines without these keywords”. You can use more than one keyword or key-phrase. Put them on separate lines. The block filter works similarly. You use a block filter to ignore a large block of text; more than one line. This is useful to filter out text advertisements or random pieces of text. (You don’t have to filter out Google ads: our robot ignores them anyway). You select two block markers, one for the beginning and one for the end of the block. These markers are pieces of text that usually don’t change on the page. Then you choose whether you want the text between the markers to be ignored, or the other way round: that everything is ignored except the text between the markers. If you use only one block marker and leave the other blank, it uses the beginning (or end) of the page. Tip: To know what keywords to use, check the preview that is below the form with the page and filter settings.

How reliable is the service?

There are some weird websites and web servers out there. Some sites rely on techniques that would be too dangerous or too difficult for me to implement. Some web servers out there could return unexpected data, confusing our robot. We can’t guarantee that all pages will be checked properly. The best thing is to try it out. If it doesn’t work for you, check for alternative monitoring services. Another problem is overly active spam filters, that confuse our email reports with spam and block them. Be sure to whitelist our sender address, or put it in your address book. Things we have done to improve the email reliability: The uptime of the server is quite good since it was moved to a datacenter in 2012; however, we need to reboot the server from time to time to update software. In May 2023, we suffered a long downtime because of hardware failure.

How about my privacy?

We never give out your personal information, email address or which pages you’re following to others. See the terms of use. Your visits to our website are entirely encrypted (https). The encryption is strong: the Qualys SSL test gives us an A+ grade. The password you use for our service is not saved; instead we save only a salted hash of it. That means, that if a hacker would be able to steal our user account list, they would have a really hard time figuring out your password. But you should avoid using the same password for several web services. We should warn you that the email reports are sent as plain text. That means that cyber criminals and intelligence agencies may be able to see what pages you're interested in.

Why do you ask for my name?

The name is written in the emails that we send you, and it may help to pass overly active spam filters. It doesn’t have to be your real name. I will never give out your personal information to anyone.

I didn't get the registration confirmation email.

Please check your spam/unwanted mail folder. If it's not there, just try registering again and Follow That Page will send you another email.

Can I follow non-English pages?

Follow That Page handles most character sets. But the old Simple Chinese character set GB2312 and the Japanese Shift-JIS are not supported, and there might be other exceptions. The Follow That Page robot uses existing software to convert HTML to UTF-8 encoded plain text; with my limited means, it’s impossible to fix this software. It may help to ask the webmaster of such page to convert his website to UTF-8, which is a smart thing to do anyway, because UTF supports almost any language on earth. As a last resort: you can try to convert the page using this tool: written by Kridsada Thanabulpong, but please use it with care! Kridsada wrote to me:
“I’d be happy if it could be any use to other users, but since the application is a bit buggy and slightly CPU intensive, I don’t know if I’ll run out of Google AppEngine per-day quota if more people were to use it.”

How does Follow That Page handle JavaScript?

The Follow That Page robot does not execute JavaScript, Java or Flash. I believe it is good policy to put content in plain HTML or XML and not have it depend on JavaScript or other special techniques.

Can I follow password protected sites?

No, and it will not be possible in the future. The security risks are too great. To make this work, I'd have to store your password in plain text, which is a bad security practice. If hackers would realize this, my system would become very attractive as a target. I could store your session cookies instead of your password, but the risk would be the same. Automating a login procedure would also be difficult because of the great differences between websites.

What happens if a website is down? When the page is not found (HTTP 404 error)?

You will be notified of the error. When there is a change in the situation, you will be notified again. When the site is up again, Follow That Page will compare the content to the last version from before the website broke down.

You're missing some changes! (I'm not getting any emails!)

If you were expecting change reports but didn’t get them, there are some possible causes:
  1. The change was undone before our robot saw it.
  2. You are using a filter to ignore certain parts of the page. Use the preview to check.
  3. The webmaster has forbidden our robot to access the page. Use the preview to check.
  4. Our mail got stuck in a spam filter. It may help to whitelist us or put us in your address book.
  5. The mail bounced as undeliverable. This could be a problem with your mailbox (like it’s full or it’s gone). If we get bounces, we’ll put your account on hold and we’ll not send you any more emails. We can’t notify you via email because that obviously doesn’t work! When you log in to our website, you’ll see a big red box explaining what’s going on. You can then change your email address.
  6. Check out to see if there are any problems with the service.

Why can't I check more often than once per 10 minutes?

Checking more than once per 10 minutes would be risky: it could push small websites over their monthly bandwidth limit, and webmasters may choose to block our robot.

Are there any bugs?

If you’ve found a bug or have a request for a feature, please contact me.

Who are you?

My name is Onno Zweers. I do this as a hobby. I work at SURFsara, the Dutch national high performance computing center, as a systems programmer. Since I have four kids it may take a long time before bugs are fixed and new features are built.