Checking a file without an account

You do not need an account to use the checker. Go to fetviewer.com/check and choose a .fet file. The page is called the FET helper.

The helper reads your rules and does the arithmetic. It tells you what FET cannot build, and it names the rules responsible. A large file takes a few seconds.

What happens to your file

Your file stays on your computer. The helper never uploads it.

Your browser reads the file and builds a summary. It sends that summary to our server. The summary holds no names. Every teacher, room, subject, student group, day and hour becomes a number first. The list that turns those numbers back into words stays in your browser.

Our server does the arithmetic on numbers alone. Your browser puts your names back when the answers arrive. The request carries no cookies. Our server does not save your file or its summary, and no account is created.

The pre-flight check inside the app works in the same way. It also sends a summary without names to our server, and our server does not save it. See What the pre-flight check does.

What the helper needs

The file must be a .fet file that FET saved. The helper does not read CSV files or spreadsheets.

The file must be smaller than 25 MB. Real timetables are much smaller than this.

What you get back

The helper opens with one sentence that says whether FET can build this file. Below it, the findings sit in groups. A group appears only when it has something in it.

Proven impossible. Arithmetic, not a guess. FET cannot build these. Open one to see the rules behind it.

Mistakes. Something here is probably not what you meant. A rule that names a switched-off activity is a mistake, not an impossibility.

What makes this file hard. This is not a problem. It is the work the solver must do.

Rules not checked. Rule types that are in your file. The helper lists and counts them, but it has no test for them yet.

The helper also gives your file a score out of 100. Read the score as an indicator, never as a verdict. A low score does not mean FET will fail.

Two more views

Connections draws one teacher, student group or room with everything it touches. Choose a second name in Compare with to see only what the two share, or what they both need.

Own your timetable draws your week, when your file has times in it. Browse it by student group, teacher, room or subject.

Asking questions in words

The helper can also answer questions about your file. This assistant is optional and you choose where it runs. One choice keeps everything on your own computer.

See Asking questions about your timetable.

What to do next

Correct the rules in FET and check the file again. Re-checks are free. The limit is 120 checks in one hour.

If your file fits the free plan, the button below the results says Import this file — free account. Make a free account, then choose the same file again on your timetables page. There you can edit the rules directly and check again as you work.

If your file has more activities than the free plan allows, the button names the plan that holds your file. It opens the plans page.

What it cannot do

The helper reads your rules. It does not solve your timetable and it never changes your file.

It cannot tell you that a file WILL solve. It proves the impossible cases; the rest is the solver's work. See What it cannot tell you.