What these tools cover
Writing comes with small, fiddly checks. An essay has a word limit, a social post has a character limit that counts emoji differently, a list pasted from a spreadsheet is full of duplicates, and two drafts of a contract need to be compared line by line. The text tools handle those jobs instantly as you type or paste.
They fall into four groups: counting and checking (word counts, character limits, readability scores), transforming (case conversion, sorting and de-duplicating, comparing texts), generating (placeholder text, stylised Unicode text, usernames) and reference (citations and symbols).
Accuracy you can rely on
Counts are Unicode-aware, so accented letters, emoji and non-Latin scripts are counted the way people expect. Readability scores follow the published formulas, such as Flesch Reading Ease and Flesch-Kincaid Grade Level, and each tool explains how its numbers are calculated. Where a platform publishes its own rules, such as how X counts links, the counter follows those rules rather than a simple character count.
Private by default
Drafts, essays and unpublished work are exactly the kind of text people do not want stored on someone else's server. These tools run in your browser; where a tool remembers your last text so it survives a refresh, it saves it in your browser's local storage on your device, and a Clear button removes it. The citation tool is the one exception that talks to the internet: when you look up a DOI, ISBN or URL, that identifier is sent to look up the details, and the tool says so.
Tips for better results
Paste plain text where possible: formatting copied from word processors can include invisible characters that change counts. For readability, aim for the grade level of your audience rather than the lowest score, and fix the sentences the checker highlights instead of rewriting everything. When comparing two versions of a document, normalising whitespace first keeps the diff focused on real changes.