Botoi Readability API vs Check Readability

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.

Check Readability analyzes pasted text and returns nine readability scores alongside a consensus grade level. The formulas include Automated Readability Index, Flesch Reading Ease, Gunning Fog, Flesch-Kincaid Grade Level, Coleman-Liau, SMOG, LINSEAR Write, FORCAST and New Dale-Chall. The web analyzer gives feedback on complexity, sentence length and word choice. A Chrome extension adds a native Side Panel, full-page or selected-text extraction and interactive formula breakdowns; scoring happens locally without transmitting page content or selected text. Text submitted to the website is sent over an encrypted connection and kept in memory only while scores are calculated. The site says analyzed text is not logged or stored, while Google Analytics is used for page visits and browser-related information. Check Readability is free, requires no account and permits personal and commercial use. The product says readable content can support accessibility and search rankings. Its scores are statistical estimates and cannot determine whether writing is accurate, logical, appropriate or well argued. The extension supports System, Light and Dark interface modes.