The product talks. Every label, error, empty state, receipt, and email is a chance to sound like Flatpay — or like one of the dozen SaaS products that built the same checkout in 2018. These pages are the rules that keep us in the first column.
Five guides, in the order you usually need them. Voice and tone first because every other rule serves it. Localisation last because it's where the earlier choices get tested under load.
Voice and tone
One voice, many tones. The 3-word voice and how it shifts under instruction, error, and confirmation.
DocumentedStyle, grammar, and punctuation
Sentence case, Oxford commas, em dashes, contractions, lists — every micro-decision in one place.
DocumentedDate and time
Format, separators, relative dates, time zones, and the locale exceptions across the eight markets.
DocumentedCurrency
European format, prefix vs. suffix, negatives in orange, slashed zero — the numerical recipe every metric inherits.
DocumentedLocalisation
Default British English, eight markets, ten languages — and the rules that keep translation from breaking the layout.
Documented