http://onionq2p24l4dshdixymmqk5bo3iar4sbama5uwcc7nz45vpio6xlxqd.onion/basic-theory-2
Bad part is that none of services that advertises by that does that.
If you can use blockchain explorers and try their service you can prove it. Third - pool mixers. You deposit some funds, you receive some funds out
of the same wallet. Bigger the pool, better the privacy.