ledger-mode in Emacs has some excellent account and description auto-completion (warning, may require a bit of configuration to suit your taste). hledger add,

ledger-mode in Emacs has some excellent account and description auto-completion (warning, may require a bit of configuration to suit your taste). hledger add, hledger-iadd and hledger-web are some of the data entry uis with auto completion. Alternatives: other ways of generating entries means less manual data entry, such as copy/paste in your editor, predefined templates (org-capture, yasnippet or equivalents), or conversion from bank csv data. [PS I realize now you were asking for more than account name auto-completion, ie: filling in defaults for all postings (legs) when you reuse a transaction description. I don't know of many PTA tools doing this yet; hledger add is one.]