Adding Comments to a Blog with Giscus

I wanted comments on my blog posts but didn't want to manage a database, deal with spam moderation, or pay for a service like Disqus. Giscus solved all of these problems by using GitHub Discussions as the backend.

Why Not a Database?

Traditional comment systems require:

• A database to store comments
• User authentication (or dealing with anonymous spam)
• Moderation tools and time spent moderating
• Backup and maintenance overhead

For a technical blog where readers likely already have GitHub accounts, this felt like unnecessary complexity.

Why Giscus?

Giscus is an open-source commenting system that stores comments as GitHub Discussions in your repository. Benefits:

• No database - GitHub hosts everything
• No spam - Commenters must authenticate with GitHub
• Free - No cost, no limits
• Markdown support - Code blocks, formatting, all work
• Reactions - GitHub's emoji reactions built in
• Thread per post - Each blog post gets its own Discussion

The tradeoff: commenters need GitHub accounts. For a technical blog, this is actually a feature - it filters for the intended audience.

Setup Steps

1. Enable GitHub Discussions

In your repository settings, scroll to the Features section and enable Discussions.

2. Create a Category for Comments

Go to the Discussions tab and create a new category. I named mine "Blog Comments" with the Announcements format (only maintainers can create new discussions, but anyone can reply).

This prevents random discussions from appearing - Giscus creates them automatically when someone comments on a post.

3. Configure Giscus

Visit giscus.app and fill in:

• Repository: username/repo-name
• Discussion Category: Select your "Blog Comments" category
• Mapping: I chose pathname so each URL gets its own discussion
• Features: Enable reactions, put input at top
• Theme: Match your site (light, dark, or custom)

Giscus generates a script tag with your configuration.

4. Add to Your Site

For an ASP.NET MVC Razor view, I added the script directly to the post template:

<section class="py-16 border-t border-neutral-200">
    <div class="max-w-4xl mx-auto px-6">
        <h2 class="text-xs font-semibold text-neutral-400 uppercase tracking-widest mb-8">
            Comments
        </h2>
        <script src="https://giscus.app/client.js"
                data-repo="username/repo-name"
                data-repo-id="R_kgDOxxxxxx"
                data-category="Blog Comments"
                data-category-id="DIC_kwDOxxxxxx"
                data-mapping="pathname"
                data-strict="0"
                data-reactions-enabled="1"
                data-emit-metadata="0"
                data-input-position="top"
                data-theme="light"
                data-lang="en"
                data-loading="lazy"
                crossorigin="anonymous"
                async>
        </script>
    </div>
</section>

The data-loading="lazy" attribute means the comments don't load until the user scrolls to them, keeping initial page load fast.

How It Works

When a visitor comments:

1. They click the comment box and authenticate with GitHub
2. Giscus creates a Discussion in your repo (if one doesn't exist for that pathname)
3. The comment is stored as a reply to that Discussion
4. Other visitors see comments loaded from the Discussion API

Each blog post URL maps to its own Discussion thread, so comments stay organized by post.

One Discussion Per Post

I initially wondered if this would create one giant thread for all posts. It doesn't - the data-mapping="pathname" setting means:

• /Blog/Post/ssl-automation → creates Discussion for that specific pathname
• /Blog/Post/john-deere-fuel-pump → creates a separate Discussion

Giscus handles this automatically. You'll see individual Discussions appear in your repo as people comment on different posts.

Theming

Giscus supports several built-in themes:

• light / dark - Basic themes
• preferred_color_scheme - Follows system preference
• transparent_dark - For dark backgrounds
• Custom CSS URL for full control

For my light-themed site, the default light theme blends well without additional styling.

The Result

Comments that:

• Require no backend code or database
• Are automatically spam-filtered (GitHub auth required)
• Support full Markdown formatting
• Cost nothing to run
• Are stored in a place I already back up (my GitHub repo)

Setup took about 15 minutes. The hardest part was deciding which Discussion category format to use.

Reference

• Giscus - The configuration tool
• Giscus GitHub - Source and documentation
• GitHub Discussions must be enabled on your repository