How to vibe codeGrammarly
AI-powered communication and productivity platform
grammarly.com ↗Productivity / AI Writing
The verdict: can you vibe code Grammarly?
Build a web-based text editor subset with AI grammar checks instead of paying, but keep paying for the universal browser extensions and native apps.
Replicating Grammarly's core web editor dashboard with an AI grammar checker and paragraph rewriter is a solid multi-week coding effort. However, cloning the real-time universal browser extensions that inject inline underlines and floating suggestion widgets into arbitrary web inputs (like Gmail, Google Docs, and custom enterprise forms) without breaking host page scripts is an engineering nightmare. Furthermore, running real-time keystroke checks over LLM infrastructure without incurring ruinous API bills requires building a sophisticated hybrid routing proxy.
Estimated effort: 6-8 weeks of intensive development
What you can't replicate
- Universal browser extension integration across every active web input field on the internet
- 17 years of proprietary grammar rules, datasets, and linguistic heuristics
- Enterprise security certifications, non-training guarantees, and SOC 2 compliance
- The full acquired Superhuman and Coda productivity suite ecosystem
Founded
2009
Raised
$1.7B+
Team
1,000+
Cheapest paid tier
$0 USD / month
What Grammarly does
Real-time writing assistance, spelling and grammar corrections, tone adjustments, full-sentence rewrites, plagiarism checking, and generative AI features.
Core features
- Real-time DOM text monitoring and inline correction highlighting
- Grammar, spelling, and punctuation check engine
- Tone detection and adjustment suggestions
- Full-sentence paragraph rewriting via LLM
- Plagiarism checking against document corpus
- Generative AI chat assistant and prompt execution
- Cloud document editor dashboard
- Browser extension surface area for injecting widgets into third-party inputs
The business
Pricing
- Free$0 USD / month
- Pro$12 USD / member / month
- EnterpriseCustom
Funding
$1.7B+ from General Catalyst, IVP, Spark Capital, Baillie Gifford, BlackRock, Breyer Capital
Pay vs build, cumulative
Break-even at month 11 — after that, every month is money kept.
The hard parts of vibe coding Grammarly
- Real-time text streaming and debounce architecture across arbitrary DOM nodes without memory leaks or UI lag
- Cross-platform distribution (4 major browser extensions, native desktop wrappers, mobile keyboards, web editor)
- Cost-aware hybrid LLM routing (fast heuristics for basic grammar, heavy models for complex generative rewrites)
- Enterprise security compliance (non-training guarantees, confidential mode, SOC 2 Type II)
How to vibecode Grammarly
Prerequisites
Node.jsfree
Runtime environment for building and executing the web application stack.
GitHubfree
Source control and deployment pipeline integration.
Anthropic API Keypay-as-you-go
Provides frontier language models for paragraph rewrites and advanced tone analysis.
AI coding tools
Recommended stack
| Frontend | Next.js |
|---|---|
| Backend | Next.js Server Actions / API Routes |
| Database | Neon |
| Auth | better-auth |
| Payments | None (personal clone) |
| Other | Tailwind CSS, TipTap / Prosemirror Editor, Anthropic API |
Build guide
01Project Scaffolding and Database Schema
Initialize the Next.js project with Tailwind CSS, configure better-auth with a local SQLite/Neon Postgres adapter, and set up database schemas for users, documents, and writing stats.
Create a new Next.js project using TypeScript and Tailwind CSS. Install better-auth and configure database connections to Neon Postgres. Set up database migrations for users, documents (storing title, content, word count, readability scores), and ai_prompts logs. Implement a clean dashboard layout with a sidebar for managing documents and tracking daily writing metrics.02Rich Text Editor Dashboard Integration
Integrate a modern rich text editor (such as TipTap or ProseMirror) into the web application to serve as the core Grammarly Editor clone interface.
Install TipTap rich text editor in the Next.js application. Build a custom editor toolbar supporting headings, bullet lists, bold, italic, and inline word/character counters. Implement auto-saving of document content to the Neon Postgres database with a debounce timer and visual save status indicator ('All changes saved' vs 'Saving...').03Real-Time Grammar & Spelling Inspection Engine
Build a background analysis worker that debounces text input, sends chunks to a fast LLM or grammar heuristic endpoint, and returns correction metadata.
Implement a client-side hook that debounces text changes in the TipTap editor by 1.5 seconds. When triggered, send the plain text payload to a Next.js API route. The API route must call Anthropic Claude Haiku with a strict JSON-mode system prompt instructing it to identify spelling errors, grammatical mistakes, and clarity issues, returning an array of fixes with start/end character offsets, error type, and suggested replacement.04Inline Suggestion Cards & UI Overlays
Render interactive underline decorations and floating tooltip cards inside the rich text editor when hovering over identified grammar mistakes.
Build a custom TipTap extension or floating overlay system that renders red/blue wavy underlines beneath text spans corresponding to the correction offsets returned by the inspection API. When a user clicks an underline, display a floating popover card showing the explanation, original text, and a one-click 'Accept' button that swaps the text in the editor state.05Generative AI Rewrites & Tone Adjustment Panel
Add a sidebar panel for generative AI features, allowing users to rewrite selected paragraphs for tone (formal, confident, friendly) or generate text from prompts.
Create a collapsible sidebar panel in the web editor named 'AI Assistant'. When text is highlighted in the editor, present quick action buttons: 'Improve clarity', 'Make professional', 'Shorten', and 'Expand'. Hook these buttons up to a streaming API route utilizing Anthropic Claude Sonnet that streams generated paragraph rewrites into a preview box with a 'Replace Selection' button.
Cost vs paying for Grammarly
What will you build it with?
Starting total with Claude Code$0 one-time
Starting costs (one-time)
- AI coding tool subscription$20
Total~$20 one-time
Ongoing costs (monthly)
- Anthropic API usage for text checks & rewrites~$5-15/mo
Total~$5-15/mo
Paying for Grammarly
$12/mo (Pro)
Your time to build
45 hours
AI tool credits
$20 (Cursor/Claude Pro)
Break-even
Never (built for learning and personal web editing)
Vibe code Grammarly: FAQ
- Can you vibe code Grammarly yourself?
- Serious undertaking — 42/100 vibecodeable. Build a web-based text editor subset with AI grammar checks instead of paying, but keep paying for the universal browser extensions and native apps.
- How long does it take to vibe code Grammarly?
- 6-8 weeks of intensive development — roughly 45 hours of hands-on time with an AI coding agent.
- How do you build your own Grammarly?
- Scoped to personal use: Next.js on the front, Next.js Server Actions / API Routes behind it, Neon for data. Follow the 5-step build guide on this page — each step has a paste-ready prompt for an AI coding agent.
- How do you code your own Grammarly without being an expert?
- Use an AI coding tool (Claude Code or Cursor) and work in small steps: scaffold, data model, core screens, then deploy. Realistic effort: 6-8 weeks of intensive development. The prompts on this page are written so the AI does the heavy lifting.
- How much does it cost to vibe code Grammarly instead of paying?
- About ~$20 one-time to start and ~$5-15/mo to run, versus $12/mo (Pro) for Grammarly. Break-even: Never (built for learning and personal web editing).
- What stack should you use to vibe code Grammarly?
- Next.js; Next.js Server Actions / API Routes; Neon; plus Tailwind CSS, TipTap / Prosemirror Editor, Anthropic API.