Readability Score API — Analyze Text Readability with Multiple Metrics
Calculate readability scores for any text using Flesch-Kincaid, Gunning Fog, Coleman-Liau, and SMOG formulas. Free API.
What is Readability Scoring?
Readability scoring measures how easy a text is to read using standard formulas. The API calculates Flesch Reading Ease (0-100, higher is easier), Flesch-Kincaid Grade Level, Gunning Fog Index, Coleman-Liau Index, SMOG Index, and Automated Readability Index. It also reports average sentence length, average syllables per word, and total statistics.
How to Use It
Call GET /api/v1/readability?text=The+cat+sat+on+the+mat. Returns { flesch_reading_ease: number, flesch_kincaid_grade: number, gunning_fog: number, coleman_liau: number, smog: number, automated_readability: number, avg_sentence_length: number, avg_syllables_per_word: number, word_count: number, sentence_count: number }.
Understanding Scores
Flesch Reading Ease: 90-100 (very easy), 60-70 (standard), 0-30 (very difficult). Grade level scores represent US school grade level needed to understand the text. Aim for grades 6-8 for general audiences.