- Bitcoin Core 0.21.0 supports Tor V3 addresses.
- Users may set precise fees denominated in satoshis, rather than estimations denominated in bitcoin.
- Consensus rules have changed for Taproot, which allows for smart contracts using Schnorr signatures.
- Taproot is fully live on bitcoin's signet, one of three official developer sandboxes. (Taproot will activate later this year, and most major mining pools have pledged support for Taproot.)
- The software supports a client-side, block-filtering system for "light clients" that do not download bitcoin's full blockchain.
- Bitcoin Core 0.21.0 supports descriptor wallets that use scripts instead of keys to execute functions.
- Bitcoin Core 0.21.0 supports SQLite.