Just rarely works well. Can't even properly block 500 accounts and still will trigger a force logout. It'll get maybe 200-300, but after continuous logouts and an eventual temporary suspension, it's just no use for accounts of 5,000 or more

The Red Block extension provides several tools for blocking or muting groups of accounts–up to 100,000 at a time-on Twitter. You can target groups of accounts following or followed by a certain Twitter account, or all of the accounts that have retweeted or liked a particular tweet. The extension does not block every account in a group reliably on the first run–as explained by the developer, this is due to the Twitter API the extension must use to block/mute large amounts of accounts at once. However, you can save accounts within the extension to run another session of blocking or muting later. You can also un-block or un-mute groups of accounts defined in the same way as above, and without the reliability issues of blocking/muting accounts. I have found it to be a perfect replacement for Twitter Blockchain.

The 500 blocking cap is really not enough. Hope Twitter can improve this though. The addon itself works as it says.

Looks like a very worthy successor to Twitter Block Chain--well done!

much better than twitter block chain, but please at least allow blocking for the first 100,000 people for large accounts instead of completely disallowing blocking