Building a Real-time Markdown Previewer with Next.js

How we built a fast, client-side Markdown editor using Next.js and Tailwind CSS. A look behind the scenes at CheetSet's development.

Why We Built It

While writing content for this blog, we constantly needed a quick way to check our Markdown syntax. Existing tools were either too complex, required login, or sent data to a server. We wanted something simple, fast, and entirely client-side.

The Tech Stack

To achieve our performance goals, we chose a lightweight modern stack:

• Next.js 14: For the framework and routing.
• React Markdown: For safe and fast parsing.
• Tailwind Typography: For beautiful, automatic styling.
• Lucide React: For crisp, consistent icons.

Key Challenges & Solutions

1. Real-time Performance

The biggest challenge was rendering large markdown files without blocking the main thread. We utilized React's memo and optimized the re-rendering process to ensure typing always feels instantaneous, even with complex documents.

2. Security (XSS Prevention)

Allowing users to render arbitrary HTML is risky. We implemented strict sanitization to prevent Cross-Site Scripting (XSS) attacks while still allowing safe HTML tags often used in documentation.

3. Dual-Pane Layout

We designed a responsive split-view that works perfectly on desktop but collapses largely on mobile, giving priority to the preview content while keeping the editor accessible.

The Result

The final tool is less than 50KB gzipped and loads instantly. It supports GitHub Flavored Markdown (tables, strikeouts) and syntax highlighting for code blocks.

What's Next?

We're planning to add features like PDF export and direct GitHub Gist publishing. Stay tuned!