I had one of my transaction stuck for quite long time. I tried some free bitcoin accelerators but it had no impact on the speed the transaction. Later the transaction got confirmed on its own. So I feel that these free BTC accelerators are just marketing gimmick to sell their paid options or to drive traffic on their sites. Do you agree with this ?
As far as experience goes, Viabtc seems to work, (
https://www.viabtc.com/tools/txaccelerator)
They have the free and paid services, haven't tried the paid though, but usually the free services is enough for everyone although there is a cap as to the number of transactions they can talk in an hour.
And as per their website, they have help accelerated 741909 transactions. And they are one of the first to offer this kind of services since 2018, so I think there is no gimmick from their end. Not sure about others though.