Ledger

Ledger is a mature command-line accounting system that implements double-entry bookkeeping in plain-text files. It's been actively maintained since 2003 and powers sophisticated financial workflows for accountants and personal-finance enthusiasts. You write transactions in a human-readable format, then Ledger generates reports, balances, and exports to CSV for spreadsheet analysis.

Ledger suits developers and technically comfortable users who want complete transparency and version control over their finances. It's excellent if you already work in a terminal, use Git, and want your financial data in plain text. Unlike graphical personal-finance apps, Ledger has no learning curve for command-line users but rewards that investment with power and customization.