Url Shortener

Implementation Details

I used Dart/Flutter to write the entire stack. Frontend is flutter compiled to web. Backend uses the dart_frog framework.

Architecture is a simple server that serves the static frontend files on / and requests to create shortened urls as well as the redirects.

Dart frog does file-based routing similar to Next.js. However, I was unable to get the static content served on / and get shortened urls to route to /[slug] so I added them to a sub-route /u/[slug].

How to Run

Running with Docker (Simpler)

With docker installed, cd into the new_backend/build/ directory where the Dockerfile is located. Build the docker image with

docker build -t <image_name> ./

Once built, run it with:

docker run -d -p 8080:8080 <image_name>

The container port is hard-coded, so you have to use the internal port 8080, the host can be whichever port.

Running the local dev server

• Install dart
• Install dart_frog

Then run the backend with:

cd new_backend/ && dart pub get && dart_frog dev

Testing

I wrote some unit tests to get the url shortening to work, and everything else was tested manually. I also include some asserts in the code to verify the various assumptions I made in the code.

Tools Used

I used various documentation sites, like the one for the dart_frog web framework, as well as the MDN docs for response codes.

I discovered from asking an LLM that I could use the redirection status codes to do the url resolving, but otherwise referenced the docs to decide to use 308.