Privacy · Plotroom

Plotroom has no accounts, no email sign-up and no analytics service. Fonts and Plotroom’s own scripts are served from this site. The only outside service its pages load is the adengine.us banner described under Advertising; it also counts one page view per page as a daily total. Checked answers, Plot Logs and printable worksheets load nothing from other sites.

Checking a problem

Your answers are sent to the server to be checked and are not stored, unless the problem is saved to a Plot Log.

Plot Logs

A log holds its name and, for each saved attempt: the skill, the problem number, how many answers were right, the answers you typed and when. It opens at a private link. We store only a one-way hash of the link's key, so we cannot find a log for you or recover a lost link. Logs not opened for 400 days are deleted with their attempts. You can delete a log yourself from its page.

In your browser

When you open a log, your browser remembers its key (in local storage) so that the next problem you check is saved to it. It stays on your device; the log page has a button to make the browser forget it. Forms carry a security cookie that only guards against forged form posts.

Server records

To stop abuse, the site counts how many logs and saves come from an address each hour and day. It keeps only a salted hash of the address, and the counts are deleted after two days. The hosting server keeps its own access logs for a limited time for security.

Payments

Checkout is not switched on (preview). When it is, PayPal will handle the payment; Plotroom will keep only a pass key's hash, the plan and the paid-until date, never card details.

Advertising

The home page, the practice index and practice problems, the worksheets index, the Plot Log start page, the method, how it works and pricing pages each show one banner ad from AdEngine (adengine.us), the small ad network run by WeldonPC, the company behind this site. For now the ads are for WeldonPC’s own services. Checked answers, Plot Logs, printable worksheets, this page, the terms and error pages show no ad.

To show an ad, your browser loads a script from adengine.us, asks it for one banner, loads the banner image, and reports once that the page was viewed and once that the banner was shown. Like any website, adengine.us receives your IP address and your browser type with those requests. The requests name this site; they never carry the address of the page you are on or your answers.

No cookies, no profile. AdEngine sets no cookies, gives you no ID and does not track you from site to site. It does not read the Plot Log key your browser keeps.
How your IP address is used. adengine.us looks up the approximate city for your IP address in a location database kept on its own server (nothing is sent to anyone else), so that ads meant for one area are shown only there. It also uses the address to count each ad view or click only once and to leave out robots and WeldonPC’s own office traffic. The address is not stored with the counts; the temporary entries made from it expire within six hours and are cleared from the server within two days.
What is kept. Daily totals only: page views for this site, and views and clicks for each ad. The adengine.us web server also keeps a standard access log (IP address, time, address requested, referring site, browser) for security; it is deleted on a rolling schedule.
Clicking an ad passes through adengine.us, which counts the click, and then opens the advertiser’s site, which has its own privacy policy.
Nothing about you is sold or shared.