# Building my own URL shortener

As I was looking into the different options to Publish on my Own Site, Syndicate Elsewhere (see POSSE), I came across the idea of having a custom permashortlink service.

Blog posts permalinks are usually quite long. On this website, for example, they include publication date as well as the full title of the post. Using long & explicit URLs is considered a good practice from a SEO standpoint, but also comes with a few drawbacks. It makes URL difficult to read, and possibly annoying to select/copy or type. Additionally, it also used to be an issue when sharing on Twitter, even though it’s not a problem anymore. Short links, on the contrary, are easier to remember, and more convenient when one’s need to type it manually (when displayed on a slide-deck during a presentation for example).
More than anything, I thought it was a nice pet project to work on. One that could be shipped in a reasonable amount of time, and could be a nice addition to my website.

## Step 1: Getting a personal short domain

That one was not that difficult. As I already own audard.net, and host this site on olivier.audard.net, I decided to go with o.audard.net. It’s not the shortest possible domain, but it’s short enough. Plus, I didn’t want to buy a new domain just for this, and setting up a new DNS record looked simple enough for a pet project.

## Step 2: Deciding how to shorten URLs

That part gets slightly less trivial. There are a few interesting examples on permashortlink page. Using an algorithmic solution is a nice idea as it doesn’t require saving anything in a database and most likely maintain a decent level of readability for humans.
I couldn’t find any ready-to-use JavaScript implementation besides whistler. On that one, I found the sexagesimal epoch days date encoding it uses not so readable for most people. It also adds some complexity to the implementation and I wanted something easy to maintain, even if I had to come back to it in a few years from now…

I finally decided to implement my own solution, mostly inspired from Whistle, but with a few simplifications on the design.

It goes as below:

• My posts have a permalink URL matching the following pattern: https://olivier.audard.net/CATEGORY/YYYY/MM/DD/TITLE/
• CATEGORY: There are only 2 different categories at the moment, articles and notes, but there might be more in the future
• YYYY/MM/DD/: this is the publication date of the post
• TITLE/: The full title of the post, which might be quite long depending on the content.
• Permashortlinks are matching the following: https://o.audard.net/CYYYYMMDDN
• C: The first letter of the category (a for articles, n for notes)
• YYYYMMDD: Publication date again, but without any unnecessary slash.
• N: The last character is the Nth post of that category on that day.

Using only the first letter from the CATEGORY looks good enough for my use-case. It’s not as robust as the original design, but as I don’t plan to have many different categories in the future, I should be fine.
N as the last character is useful to distinguish between 2 different posts on the same day. As I don’t publish that much content, I initially thought I could skip that part, but as I’m planning to

## Step 3: Implementation

Implementation goes in 3 different parts:

1. The shorten/expand algorithmic logic lives on dharFr/url-courte(GitHub) and has been published on NPM under @dhar/url-courte.
2. The redirection logic lives on its own microservice, using Netlify’s serverless functions. Converting the N ordinal was the more tricky part, as Hexo blog engine doesn’t provide this data out of the box. I finally choose to fetch my blog JSON feed and filter the result on a specific date to find the correct post. It’s probably not optimal, but it’s good enough for now. Once the URL is expanded, the service return a 302 redirect to the correct URL on the principal domain.
3. Displaying shortlink in the article meta is achieved thanks to a custom Hexo helper.

## All done!

Good. Now I have my own custom URL shortening service. Maybe not the most useful feature, but it was interesting to build and a good opportunity to learn more about Netlify serverless functions. And it’s also quite rewarding to be able to share my own shortlinks instead of using 3rd party solutions as I used to do in the past. It feels like I have more control on the content I publish online, and that’s pretty cool.