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The tech blog commenting system with utterances

Introduce a project called utterances that I recommend for a commenting system for technical blogs.Also introduce utterances-component, a project that can handle utterances as a component.

4/1/20227 min read
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Getting Started

When you create your own blog, you may wonder about the comment function. Do you want to create it yourself or use an external service?

I've used Firebase firestore and Firebase Authentication to create a comment system for anonymous users. However, if you have a technical blog in mind, wouldn't you like to have the following features?

  • User authentication
  • Write in markdown format
    • Embed links.
    • Links should be noreferrer
    • Images can be embedded
    • XSS protection
    • Can be previewed
  • Comment notification
    • Notify the blogger
    • Notifications to commenters

Also, I think most blogs these days are made with static site generators, so I would like to use the above features in a serverless way.

Personally, I've been obsessed with blog features and have experienced frustration, so I want to make the unrelated parts easy.

In such cases, I recommend utterances.

What are utterances?

utterances is not a blogging system.

The official description is as follows.

A lightweight comments widget built on GitHub issues. Use GitHub issues for blog comments, wiki pages and more!

utterances provides a lightweight comments component and a bot for commenting on GitHub issues. With utterances, you can connect GitHub issues to articles and pages, and display the issues.

In other words, it is almost the same as embedding a GitHub issues into a blog.

The authentication uses GitHubOAuth, and can be written in markdown format or any other way you like. There are also several color themes that support dark mode, and you can even specify issue labels.

It's also free and has no ads.

Features of utterances

Let's see if it meets the requirements for a technical blog commenting system.

User authentication

For user authentication, we will use the GitHubOAuth flow. If it's a technical blog, the target audience is technical people, so This is probably the most ideal authentication provider. For security concerns, anonymous users cannot comment, though.

Can you write in markdown format?

You can write comments as you would write an issue on GitHub. You can write comments as if you were writing an issue on GitHub, as you can see from this blog. It also looks the same. The only difference is that there is no shortcut widget for markdown notation. You can also preview it, so no complaints there.

Comment Notifications

As I mentioned earlier, commenting is the same as commenting on a GitHub issue. So the blogger will get a notification from GitHub. Commenters will also be notified of other comments as well.

The above is all the functionality you need, but there are a few other things worth mentioning.

Reactions to comments

As with GitHub issues, you can react to comments. You can add 🚀 or ❤️ ,etc to the comment. It also works reactively, just like the original.

There are similar projects such as Gitment and Gitalk, but the closest in appearance and functionality to GitHub issues is utterances.

Options for tying to various GitHub issues

There are six ways to tie an article to GitHub issues. You can choose from the following methods for the title of the issue:

  • Partial match with the pathname of the page
  • Partial matching with the URL of the page
  • Partial match with the title of the page
  • Partial match with the og:title of the page
  • Contains a specific term

This means that if the tied issue is not found, the comment will not be displayed in any way. When a comment is posted, the comment will be added to the associated issue, if one exists. If not, an issue will be created automatically.

It is also possible to specify an issue number to tie.

This variety of association options allows for flexible support of blogs with complex path structures.

For example, in the case of an internationalized blog like this one, there are articles with the same content in different languages and with different pathname.

In this case, you can choose whether to unify the comments for the articles or separate them.

In the case of above URL, this blog wanted to have separate comments for the Japanese and English articles, so I chose to tie them by pathname.

The title of GitHub issues generates posts/comment-system/ and en/posts/comment-system/.

Since it is the longest match, you can distinguish them without any problem even if the article is in English.

On the other hand, if you want to unify the comments, you can specify the slug as a specific term that matches in both articles.

Install utterances

Installation is very easy. There are two things to do. The first is to install the utterances-bot in your GitHub App.

This bot will write comments on real GitHub issues.

The other is to load the utterances script.

Just place the script tag generated according to the official documentation in your HTML and you are done. The script tag looks like this


Introduction to the UI component library

React, Vue or Svelte, etc working with script tags in these requires a bit of tricky stuff.

In order to handle script tags in React, Vue, Svelte, etc, you need to be a little hack.

So I made a utterances-component. It currently supports React/Preact, Vue3, and Svelte. What it does is not much, but it can be handled as a component, so it should be easy to implement utterances.

import { Utterances } from 'utterances-react-component'

Since this project was built with monorepo. If there are other UI component libraries that you would like to see supported, please submit a feature request.

Limitations of utterances

I have only introduced the good points, but there are some limitations.

Can't get the comment count

If you have a blog, you would like to display the number of comments in a different place as well. Unfortunately, it is not possible to get the number of comments.

The utterances script actually embeds an iframe. Therefore, due to CORS, you can't even access the DOM. So you can't even extract the number of comments from the string xxx Comments - powered by

If you self-host the script, you can use the postMessage API for messaging since it is an iframe.

See Comments counts #36 for details.

Note that this blog uses GitHub APi v4 separately to get only the comment count of an issue.

Rate Limits

utterances makes a request to GitHub issues to get comments. High frequency requests will be trapped by GitHub's rate limit.

For example, if a comment is fetched too many times due to frequent reloads, the comment becomes unusable.

If you don't mind the above points, I recommend you to try it.

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