Botoi Readability API vs Delimiter Readability Checker

Botoi Readability API analyzes English text and returns Flesch-Kincaid Grade, Flesch Reading Ease, Gunning Fog, and underlying counts. A request sends a required text string to POST /v1/text/readability and receives JSON. Flesch Reading Ease scores run from 0 to 100, with higher values indicating easier reading; Gunning Fog estimates the years of formal education needed. The formulas and syllable heuristics are calibrated for English, so grade mapping is not meaningful for other languages. Botoi recommends sending at least 100 words because short samples can produce unstable scores. Suggested uses include enforcing plain-language standards, reviewing legal or medical drafts, refining blog posts for SEO, and comparing writing across authors. Examples are provided in cURL, JavaScript, TypeScript, Python, and Go. The Free plan is free and lists 1,000 requests per day and 10 per minute; the endpoint page separately states five requests per minute for its free tier. Starter costs $9 a month. Requests above a per-minute or daily cap receive HTTP 429, and daily limits reset at midnight UTC.

Delimiter Readability Checker is a free web tool that scores English text with Flesch Reading Ease, Flesch–Kincaid Grade, and Gunning Fog formulas. It shows sentence and syllable averages behind the scores, updates results automatically in the browser, and does not send entered text to a server. A Load file control accepts text, and a Copy control copies results. The page suggests checking public-facing copy, plain-English requirements, long articles, and draft rewrites. It includes sentence analysis and clarity recommendations, and no account is required. The formulas were calibrated on English prose, so scores for other languages are not meaningful. They assess sentence and word length rather than clarity, accuracy, or structure. Syllable counting is heuristic, so individual words may be counted incorrectly. The tool has a free plan at free, with no paywall. Support is available at [email protected], although replies are not instant and no response time is promised.