Double-entry, plain-text accounting you can audit line by line. Web interface for the open-source Beancount ledger format — good for founders and freelancers who want real books without a subscription suite.
From the site: Plain-Text Accounting. Powerful, Precise, Auditable.
Why I recommend it: If spreadsheets are getting messy but QuickBooks feels like overkill, this is the middle path — your books stay in a file you own.
Investopedia's plain-English explainer on contribution margin — sales revenue minus variable costs — with worked examples and how to use it for pricing and product decisions.
From the site: Discover how to calculate contribution margin, a key profitability metric, by subtracting variable costs from sales revenue.
Why I recommend it: If you sell anything, know this number before you set a price. It tells you what each sale actually contributes after variable costs.
