Krtk is an open-source URL shortening application. Written in Go, it aims to provide a simple, efficient, and easy-to-deploy solution for generating short links. The app was created out of a desire for a straightforward URL shortener that is both user-friendly and quick to set up. Key features of Krtk include the ability to quickly shorten URLs, CAPTCHA protection to prevent automated abuse, and a lightweight SQLite database for easy deployment. It also offers a minimalist web interface that prioritizes simplicity and functionality. In this step by step guide I will show you how to install Krtk on your Synology NAS using Docker & Portainer.

• STEP 1

Please Support My work by Making a Donation.

• STEP 2

Install Portainer using my step by step guide. If you already have Portainer installed on your Synology NAS, skip this STEP. Attention: Make sure you have installed the latest Portainer version.

• STEP 3

Make sure you have a synology.me Wildcard Certificate. Follow my guide to get a Wildcard Certificate. If you already have a synology.me Wildcard certificate, skip this STEP.

• STEP 4

Go to Control Panel / Login Portal / Advanced Tab / click Reverse Proxy. Follow the instructions in the image below.

• STEP 5

Now click the “Create” button. Follow the instructions in the image below.

• STEP 6

After you click the Create button, the window below will open. Follow the instructions in the image below.

On the General area, set the Reverse Proxy Name description: type in Krtk. After that, add the following instructions:

Source:
Protocol: HTTPS
Hostname: krtk.yourname.synology.me
Port: 443

Check Enable HSTS

Destination:
Protocol: HTTP
Hostname: localhost
Port: 3437

• STEP 7

On the Reverse Proxy Rules, click the Custom Header tab. Click Create and then, from the drop-down menu, click WebSocket. After you click on WebSocket, two Header Names and two Values will be automatically added. Click Save. Follow the instructions in the image below.

• STEP 8

Go to Control Panel / Network / Connectivity tab/ Check Enable HTTP/2 then click Apply. Follow the instructions in the image below.

• STEP 9

Go to Control Panel / Security / Advanced tab/ Check Enable HTTP Compression then click Apply. Follow the instructions in the image below.

• STEP 10

Log into Portainer using your username and password. On the left sidebar in Portainer, click on Stacks then + Add stack. Follow the instructions in the image below.

• STEP 11

In the Name field type in krtk. Follow the instructions in the image below.

Note: Copy Paste the code below in the Portainer Stacks Web editor.

services:
  krtk:
    image: ghcr.io/ajarmoszuk/krtk:latest
    container_name: Krtk
    healthcheck:
      test: ["CMD-SHELL", "nc -z 127.0.0.1 2137 || exit 1"]
      interval: 10s
      timeout: 5s
      retries: 3
      start_period: 90s
    ports:
      - 3437:2137
    restart: on-failure:5

• STEP 12

Scroll down on the page until you see a button named Deploy the stack. Click on it. Follow the instructions in the image below. The installation process can take up to a few minutes. It will depend on your Internet speed connection.

• STEP 13

If everything goes right, you will see this message at the top right of your screen: “Success Stack successfully deployed“.

• STEP 14

🟢Please Support My work by Making a Donation. Almost 99,9% of the people that install something using my guides forget to support my work, or just ignore STEP 1. I’ve been very honest about this aspect of my work since the beginning: I don’t run any ADS, I don’t require subscriptions, paid or otherwise, I don’t collect IPs, emails, and I don’t have any referral links from Amazon or other merchants. I also don’t have any POP-UPs or COOKIES. I have repeatedly been told over the years how much I have contributed to the community. It’s something I love doing and have been honest about my passion since the beginning. But I also Need The Community to Support me Back to be able to continue doing this work.

• STEP 15

Now open your browser and type in your HTTPS/SSL certificate https://krtk.yourname.synology.me in my case https://krtk.mariushosting.synology.me Type in your original long URL that you want to shorten, then type in the captcha in the apposite field. Click Shorten. Follow the instructions in the image below.

• STEP 16

Copy the shortened link and share with your friends!

• STEP 17

Your shortened link at a glance!

Enjoy Krtk!

🆘TROUBLESHOOTING

Note: If you want to run the Krtk container over HTTPS, check How to Run Docker Containers Over HTTPS. In order to make Krtk work over https, it’s also mandatory to set up WebSocket.

If you encounter issues by using this container, make sure to check out the Common Docker issues article.

Note: Can I run Docker on my Synology NAS? See the supported models.
Note: How to Back Up Docker Containers on your Synology NAS.
Note: Find out how to update the Krtk container with the latest image.
Note: How to Free Disk Space on Your NAS if You Run Docker.
Note: How to Schedule Start & Stop For Docker Containers.
Note: How to Activate Email Notifications.
Note: How to Add Access Control Profile on Your NAS.
Note: How to Change Docker Containers Restart Policy.
Note: How to Use Docker Containers With VPN.
Note: Convert Docker Run Into Docker Compose.
Note: How to Clean Docker.
Note: How to Clean Docker Automatically.
Note: Best Practices When Using Docker and DDNS.
Note: Some Docker Containers Need WebSocket.
Note: Find out the Best NAS Models For Docker.
Note: Activate Gmail SMTP For Docker Containers.

This post was updated on Wednesday / April 2nd, 2025 at 11:36 PM