While using Atcoder, I noticed some features I needed were missing, so I developed an extension — Atcoder Companion ( Link for Chrome & Link for Firefox).
The extension offers the following features:
1. Adds a status column to the list of problems (inspired by Atcoder Color) 
Provides performance and rating predictions (inspired by ac-predictor)
Allows for downloading and copying test cases with ease.
By clicking on the extension icon, you can enable or disable certain features.
The extension's source code is currently messy, so I plan to publish it once I clean it up.
If you encounter any issues while using the extension, please let me know in the comments. Any feedback or ideas for new features are greatly appreciated.
Update 1: Add link for Firefox
Update 2: Source code is available on Github
Auto comment: topic has been updated by _hoanglong_ (previous revision, new revision, compare).
Auto comment: topic has been updated by _hoanglong_ (previous revision, new revision, compare).
Wonderful Work , I still have issue with Downloading Test Cases :(
_hoanglong_ please share the settings required for Chrome on windows , Thanks !
MathModel Could you tell me more details ?
UPD : Thanks _hoanglong_ , It seems that I must restart the system so it works !
Will there be a Firefox extension of this?
David9006 Yes, of course, I will publish it to Firefox soon.
Then thank you very much for this.
David9006 Sorry, I am late.
My extension is now available on Firefox. Please check it out.
Why i cannot see the testcase download button?
Restart chrome or the operating system .
I figured it out. It (downloading testcase feature) has some conflict with "AtCoder Better!". I will appreciate if you can check it out.
AtCoder Better!, is a Tampermonkey extension, you can find it here.
xcx0902 Thank you. Let me check.
Update: I just fixed the conflict issue with Atcoder Better. Please wait a moment until it is approved.
Could you also upload it to the Microsoft Edge webstore or provide a crx?
I'd like to try it on Edge too :D
If you open that link with Edge, it will automatically have a install button for Edge.
Oh, yes! I forgot. Thanks!