How I Built a Low-Cost URL Shortener With Cloudflare KV

I am building an open-source, highly scalable, and low-cost .By low-cost I mean, just $5 per month on Cloudflare worker and a free plan for basic requirement

Idea

At DaySchedule, we had many customers upvote a URL shortener feature with auto-expirable links to book an appointment instead of sharing their original URL.

So, I decided to try Cloudflare for this project -

By leveraging Cloudflare KV's capabilities, the goal was to develop a solution that offered not only URL shortening but also customization options, analytics, and scalability, all while maintaining a significantly lower cost compared to our established services on AWS.

Features

• Expirable links using cacheTtl option on KV
• Custom domain using Cloudflare for SaaS
• Analytics using Worker analytics

API

I used hono.dev by for API routing, and it's blazing fast and offers Cloudflare pages template to build Edge projects quickly.

Here is an example of server.ts from their docs -

import { Hono } from 'hono'
const app = new Hono()

app.get('/', (c) => c.text('Hono!'))

export default app

Controller

The /links API is all I need to create, update, and manage the short links.

const links = new Hono<{ Bindings: Bindings }>();

links.post(
  '/',
  validator('json', (value, c) => {
    const parsed = linkSchema.safeParse(value);
    if (!parsed.success) {
      return c.json(parsed, 400);
    }
    return parsed.data as ShortLink;
  }),
  async (ctx) => {
    const data = ctx.req.valid('json');
    // Set expire_at if given, or fallback to 1 month expiry
    const expireAt = data.expire_at
      ? dayjs(data.expire_at).unix()
      : dayjs().add(1, 'month').unix();
    if (expireAt <= dayjs().unix()) {
      return ctx.json(
        { message: 'The expire_at must be greater then current date time' },
        400
      );
    }

    let key = data.key || nanoid(7);
    let exists = await ctx.env.SHORTLINKS.get(key);
    while (exists) {
      key = nanoid(7);
      exists = await ctx.env.SHORTLINKS.get(key);
    }
    await ctx.env.SHORTLINKS.put(key, JSON.stringify(data), {
      expiration: expireAt,
    });
    return ctx.json(
      { ...data, key: key, short_url: `//idm.in/${key}` },
      200
    );
  }
);

Code explanations -

This code is POST request to create short links. Here's a breakdown of the code to explain what I am doing:

1. const links = new Hono<{ Bindings: Bindings }>(): It creates an instance of the Hono object.
2. Validation with zod - The validator('json', (value, c) => {...}): function is used as a middleware for validating the incoming JSON payload defined in linkSchema.
3. Set expiration: Checks if an expiry date is provided in the payload. If not, it sets an expiry date one month from the current date and time.
4. Generates a unique key for the link using nanoid(7) or uses the provided key from the payload if available.
5. Stores the link data (converted to a JSON string) in the Cloudflare KV (SHORTLINKS) with an expiration time based on the calculated expiry date.

Demo

The demo is available on , it's free to use and open-sourced on Github to build your custom URL shortener.

You can clone the repo to deploy on your Cloudflare account.

Don’t forget to on GitHub to show your support :-)