Notice Regarding the Sale of AtCoder User Submissions to AI Companies and Updates to the Terms of Service and Privacy Policy — Official blog here
Posting it verbatim below
Starting in August 2026, AtCoder will begin licensing user-submitted source code to AI companies for use as AI training data.
The licensed data will include not only submissions made after the start of the program, but also source code that has already been submitted in the past. However, any submission for which AI training has been explicitly opted out will not be included.
In connection with this change, we have updated our Terms of Service and Privacy Policy. We believe this data licensing program is necessary to ensure that AtCoder can continue providing programming contests free of charge in the future. At the same time, we do not believe that users should be required to allow their submissions to be used for AI training simply in order to participate in contests.
For this reason, we have introduced an opt-out setting for AI training use that applies to all submissions, as well as a separate opt-out setting that can be configured on a per-submission basis.
We have also provided a one-month grace period during which users can review and update their preferences.
If you do not want your submitted source code to be used for AI training or included in the licensing program, please make sure to update your settings before the grace period ends. For instructions on how to change your settings, please see the following page:
How to Opt Out of AI Training (Japanese) - AtCoderInfo (https://info.atcoder.jp/overview/about/ai-training-opt-out)
AtCoder will continue pursuing new initiatives to ensure that our programming contests remain free for everyone.
Thank you, as always, for your continued support of AtCoder.
If you want to opt out
Crazy times we live in.
They have to make money
starting a year ago user submitted codes are now camouflaged AI generated codes
Maybe I'm one of the few people who think that this technology is actively harmful to us. I don't think making a statistical model train on such an enormous dataset of competitive programming submissions is useful for anything except wanting to replace people in the workforce and addicting people to these models to think for them. Ironically this may keep contests free but kill them quicker.
so what should we do? halt all progress, jail all who try to further train models to maintain status quo?
yes
deleted
yes
I'll do my part and opt out.
well it also means they can train anti cheat models?
let's be honest.
that's probably not happening.
yet still it's an implication that they can
unfortunate however i would rather this than ads on sites or costs to competitors. Also very glad they are giving opportunity to opt out which practically makes this neglible for anyone who cares. I wonder if cf will do this in future as they're servers cannot be cheap and im not sure how they are sustaining it
an opt out policy means you need to take action to not have your submissions sold to the highest bidder. someone might not want that but not hear about the policy until it's already in effect. for most things the default behavior is practically the only behavior
Even if we opt out, AI companies will still farm submissions using bots.
Yeah exactly so at least Atcoder is getting some money while they do that
Just a few years back they closed off the atcoder testcase library for this reason. Shame it might not come back anymore