The marketing or web lead at a company whose site already exists in more than one language, or the developer who inherited it and now owns the tagsNot a localisation engineer shipping software strings and resource files, not somebody buying a translation service, and not a language learner
A multilingual site is a record, not a translation job
A site in four languages is not one site translated four times. It is four hundred and eighty pages, each of which exists or does not, is current or stale, and carries tags telling a search engine which reader it is for. The worksheets here work that out from your own numbers, free and without an account: the hreflang tags your pages and locales need, the return links they owe each other, and what translating the words is going to come to at your rate. Hreflangly Pro keeps the record afterwards, one row per page per locale.
Hreflangly Pro is $17 a month for the whole site, billed monthly.