Today I had a very bad experience. I finished coding 1924C - Fractal Origami just a minute before the contest ended and when I tried to submit it, Cloudflare blocked me from doing so (this code got AC 243668438 after the testing phase, so yes, I lost rating because of this). My point is that not all of us can have a god-blessed internet connection, and Cloudflare is annoying, I lose several minutes in every contest because of this and I'm pretty sure I'm not the only one. I have to wait a month between rated contests because the Div1 frequencies are bad so please remove Cloudflare, there must be several ways to prevent DDoS attacks, choose the one that doesn't affect the contestants.MikeMirzayanov
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Codeforces (c) Copyright 2010-2026 Михаил Мирзаянов
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Время на сервере: 14.10.2026 23:27:07 (f1).
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there must be several ways to prevent DDoS attacks ... that doesn't affect the contestantsFor example?
By shutting the server down during the contests. No server, no attacks :)
qrator.ru
Same here. I coded up a solution to 1925E - Space Harbour a few seconds before the contest ended, but Cloudflare prevented it from going through.
And my problem is that Cloudflare, literally doesn't work. This leads to me using mirror.codeforces.com. Now what are the cons? First of all I can't view my own submissions, whenever I get a wrong answer on Test 1, I can't really see what's the checkers verdict. And second we got images, images won't load when i'm using mirror.codeforces.com, And I have to ask my friends to send pictures of problem images cause i can't view them. Note that this doesn't happen in other sites, but for some reason in Codeforces it's always like this.
Not a lot of other cp sites have 30000 concurrent users!
True! But by "other sites" I didn't mean cp-related specifically, I meant other sites that use CloudFlare. My real problem with CF is that CloudFlare just refreshes after I verify, and never allows me to use codeforces.com during contests.
now i am able to see my code in mirror.codeforces.com , earlier we couldn't but now they are opening
It also disrupts some tools like CCH. Cloudflare will be checking the tool forever... :(
At last somebody said
Yeah, it just doesn't allow me to use codeforces from my mobile phone, lol: Youtube
Does it have any drawback other than it is minimal?
If you get WA on test 1, you can't view the checker comment or your code's output.
even the codeforces api has the codeflare security.. i don't know what is the point of having apis then. we can't use it from a client.
We can use CDN that can help distribute traffic across multiple servers and data centers, reducing the impact of a DDoS attack.
And who is going to pay for it?
Totally agree. Even in some areas (like Iran) this happens every fifteen minutes in contest time and it's really annoying...