# How to Vibe Code Your Own Hemingway Editor (and Stop Paying for It) > Make your writing bold and clear. - Site: https://hemingwayapp.com - Category: Productivity & Writing Tools - Platforms: Web app - Verdict: **Weekend build** (88/100 vibecodeable) - Estimated effort: A weekend (12-16 hours) ## Verdict You can build a fully functional personal clone of Hemingway Editor over a weekend, but the real moat is its decade-old domain authority. The core engineering of Hemingway Editor is surprisingly straightforward: basic regex tokenizers, syllable counters, and standard readability formulas run entirely in the browser. AI coding assistants handle the text-parsing logic and highlight overlays effortlessly. The only subtle engineering hurdle is synchronizing a custom contenteditable div with an absolute-positioned highlight layer so the colors never misalign when wrapping text. Adding LLM rewrite capabilities via an API wrapper takes minutes, making this an ideal weekend project for personal use. ### What you can't replicate - The hemingwayapp.com domain authority and ten years of organic SEO rankings - Entrenched brand trust and millions of historical users ## What it does A text-editing and style-checking web application that evaluates prose through readability algorithms and flags common stylistic weaknesses via a color-coded text highlighting system. ### Core features - Real-time text highlighting overlay engine for readability rules - Syllable counting and word parsing algorithm for Flesch-Kincaid scoring - Sentence splitting and tokenization parser - Passive voice and weak adverb detection regex filters - Complex phrase checker with simpler alternative suggestions - AI sentence rewriting and tone adjustment backend integration ## The business ### Pricing - Free Web Version: Free - Hemingway Editor Classic: $19.99 - Hemingway Editor Plus: $25/mo - $30/mo Founded 2013. Team size: Small indie team. ## The hard parts - Building a content-editable text overlay that stays perfectly synchronized with user typing without lagging or cursor drift - Handling complex edge cases in rule-based syllable counting and English grammar tokenization - Managing streaming LLM rewrites concurrently with real-time local text parsing ## How to vibe code Hemingway Editor ### Prerequisites - Node.js (free): Required for running the Next.js development environment and installing packages. - GitHub (free): Hosts the git repository and connects to Vercel for deployment. ### Recommended AI tools - Claude Code: Best-in-class agentic coding tool for scaffolding the complete app and writing complex regex parsing logic. - Cursor: Excellent for iterative UI work on the text highlighting overlay and styling components. ### Stack - Frontend: Next.js with Tailwind CSS - Backend: Next.js API Routes / Server Actions - Database: None required for core personal editor (local storage or browser state) - Auth: None required for personal use - Payments: None required for personal use - Other: Anthropic API for AI sentence rewrites ### Hosting - Vercel (Hosting the Next.js frontend and serverless API endpoints for AI rewrites.): $0/mo ### Build guide 1. **Scaffold Next.js Project & Layout** — Initialize a modern Next.js project with Tailwind CSS and set up a split-screen or side-panel dashboard layout for the editor and readability metrics. ``` Create a new Next.js project using Tailwind CSS and Lucide React icons. Build a clean, minimalist desktop-style layout inspired by Hemingway Editor, featuring a top navigation bar with word count / reading time stats, a main centered writing canvas, and a right-hand sidebar for readability metrics, grade levels, and AI rewrite controls. ``` 2. **Implement Readability & Grammar Parsing Engine** — Write pure client-side utility functions for counting words, sentences, syllables, and calculating the Flesch-Kincaid grade level index. ``` Create a utility module in TypeScript that analyzes text strings for readability. Implement functions to count words, sentences, and syllables using standard heuristic rules. Calculate the Flesch-Kincaid Grade Level and Gunning Fog index. Additionally, write regex pattern matching rules to flag: 1) Very hard to read sentences (red), 2) Hard to read sentences (yellow), 3) Passive voice constructions (green), 4) Adverbs and weak qualifiers (blue), and 5) Complex words with simpler alternatives (purple). Return an array of flagged spans with start and end character indices, categories, and explanation notes. ``` 3. **Build Synchronized Text Highlighting Overlay UI** — Construct an interactive editor interface using a contenteditable container or a synchronized backdrop overlay that renders color-coded highlights seamlessly as the user types. ``` Build a robust text editor component in React that supports real-time text analysis. To avoid cursor jumping issues typical of direct contenteditable innerHTML manipulation, implement a synchronized dual-layer overlay approach: a transparent textarea where the user types overlaid on top of a styled background div that renders the text wrapped in colored span highlights based on the parser results from Step 2. Ensure precise alignment of fonts, padding, line heights, and scrolling behavior between the input and the backdrop. ``` 4. **Build Readability Metrics Sidebar & Breakdown** — Create a clean metrics panel displaying overall readability grade, reading time, word count, character count, and itemized counts for each highlight category. ``` Create a sidebar component that takes the analysis results and displays: 1) Overall readability score with a descriptive verdict (e.g., 'Grade 6, Good'), 2) Total word count, reading time, paragraphs, and sentences, and 3) Color-coded pill counters matching each highlight category (e.g., 2 adverbs, 4 passive voice). Clicking a pill should scroll or focus the user on the corresponding issue in the text. ``` 5. **Integrate AI Rewrite Backend API** — Connect an API route utilizing the Anthropic API to accept flagged sentences and return clearer, simplified rewrites on demand. ``` Create a Next.js API route that accepts a flagged sentence and an instruction (e.g., shorten, remove passive voice, simplify). Use the Anthropic API with Claude Sonnet to generate concise, clear rewrites of the sentence. Update the frontend UI to display a popover tooltip or sidebar action when clicking a highlighted sentence, allowing the user to accept the AI-generated rewrite with a single click to replace the text in the editor. ``` ### Cost vs paying **Starting costs (one-time):** - Domain name (optional): $12.00 one-time - AI coding tool subscription: $20.00 one-time - Total: ~$32.00 one-time **Ongoing costs (monthly):** - Vercel hosting: $0/mo - Anthropic API usage: ~$2-5/mo - Total: ~$3/mo - Paying for the SaaS instead: $25.00/mo (Plus tier) - Build time: 12-16 hours - AI tool credits: $20.00 (Claude Pro) - Break-even: 1 month of Plus tier ## Sources - [Hemingway Editor Official Website](https://hemingwayapp.com) - [freeCodeCamp - How I reverse-engineered the Hemingway Editor](https://www.freecodecamp.org/news/how-i-reverse-engineered-the-hemingway-editor/)