Botoi Readability API vs Text Inspector

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.

Text Inspector analyses English text for difficulty, readability, lexical diversity, and CEFR levels. Its overall difficulty score draws on more than 200 metrics, while the CEFR Level Checker gives individual words a level along with their commonness and difficulty. Listed tools include Statistics and Readability, Lexical Diversity, Scorecard, Tagger, EVP, BNC, COCA, Academic Word List and Phrases, Knowledge-Based Vocabulary Lists, and Metadiscourse Markers. An API lets people and organisations add analysis and scoring to their own products. The maker describes it as useful to language professionals, academics, and students preparing teaching materials or tests and evaluating student work. English is fully supported; other languages may receive limited statistics or lexical-diversity information. The Free plan covers 250 words and automatically deletes analysis data after six hours. The Organisation plan allows up to 13,000 words, the largest stated limit. A 30-day trial is listed for API access, which starts from £360 per year.