Generating a QR code does not require a 3rd party service. You can do it yourself. Many online QR code generators or apps on your phone are pathways that force you to paying a monthly fee to keep your generated QR code working. Frustrating.

A QR code seems like magic but really it is just a fancy way of encoding text data in an image that is easy for a computer to read using a camera.

For example, generating a QR code image for the the text string sentence: "DIY QR Codes are easy" can be done easily on a Linux system (Ubuntu / Raspberry pi OS) by installing a tool called qrencode:

sudo apt install qrencode
qrencode -o easy-qr.png "DIY QR Codes are easy"

This results in ta PNG image called easy-qr.png:

Point your phone at that image and out pops the message:

DIY QR code for your website

This means you can make a custom QR code for any website using the URL of the website through the qrencode command.

For example here is how to make a QR code for the page you are viewing now:

qrencode -o hive-qrcode.png "https://hive.mod0.org/crypt/qr-code-generation/"

Creating the following image:

QR What?

QR is short for 'Quick Response'

Fancy QR Codes via a website:

Don't have a handy Linux environment to use qrencode? Not a problem. The open source community has your back with a website to go with a qr-code library: qr-code-styling is a JavaScript library that is made available on a free to use website: qr-code-styling.com.

qr-code-styling.com makes it easy to create QR codes on the web w/o installing any tools and it gives you the ability to tweak generation options to go beyond a black and white QR code.

Here is one I did for t3alliance.org on the website

amzqr (CLI)

There are other open source tools to play with for QR code like amzqr

sudo apt install python3-pip
pip install amzqr
amzqr http://hive.mod0.org

Not that exciting - similar to before but a bit bigger.

Let us spice that up with the following t3logo.png

amzqr https://hive.mod0.org -p t3logo.png -c 

That command results in the creation of the following t3logo_qrcode.png (renamed to hive-t3-qrcode.png)

Beyond URLs and basic text

Location QR Codes

HowToGeek / Create QR Codes from command line includes examples for how to store location information. Their example is create a QR Code for Stonehenge:
qrencode -s 6 -l H -o "geo.png" "geo:51.185013,-1.859105"

Here is the command for creating a location QR code for the UAF Cornerstone Plaza:
qrencode -s6 -l H -o uaf-geo-qr.png "geo:64.856123,-147.819509"

When scanned and opened with a map app like Google Maps on Android:

SMS

SMS prompt syntax: "SMSTO:+XX-XXXXXXXXXX:Hi"

VCard

VCard,also known as VCF (Virtual Contact File), is a file format standard for electronic business cards. You make a QR codes to share your contact information.

Create a vcard.txt file using the following syntax:

BEGIN:VCARD 
VERSION:3.0
N:Lastname;Surname;Middle;;
FN:Displayname
ORG:
TITLE:
TEL;TYPE=voice,work,pref:
EMAIL:
END:VCARD

and render it as a QR code like this:
qrencode -s 9 -l H -o "contact_card.png" < vcard.txt

Example for Bugs Bunny's bugs-vcard.txt

BEGIN:VCARD 
VERSION:3.0
N:Bunny;George;Washington;Dr;
FN:Bugs Bunny
ORG: Looney Tunes
TEL;TYPE=cell:202-555-0130
TEL;TYPE=work:+1-202-555-0198
EMAIL;TYPE=work:bugs@example.com
END:VCARD

qrencode -o "bugs-vcard.png" < bugs-vcard.txt

WiFi information

The string style to encode WiFi SSID and the password:

"WIFI:S:<SSID>;T:WPA2;P:<password>;;"

Replace the <SSID> and the <password> with appropriate details. Swap out WPA2 for WEP as appropriate.

Email prompt

"mailto:<email_address>?subject=Subject&body=Body"

More Learning:

There are lots of other ways. I recommend the following resources to learn more, like getting a free open source GUI (graphical user interface) or other features:

• MakeUseOf.com / Best QR code generator apps for Linux which covers: qrencode (CLI), QR generator (GUI), Decoder (GUI), QtQR (GUI), Zint (CLI & GUI)
• MakeUseOf.com / Create QR Codes in Linux covers many of the examples above in more detail.

Segno (Python)

The Segno tool provides both Python QR Code and Micro QR Code encoders plus a command line tool for generating QR codes similar to qrencode. Worth checking out if you are a python hacker.

rqrcode (Ruby)

The rqrcode library unleashes Ruby programmers. Used to write dazzler/zerkqr a silly tool that generates ASCII based QR codes in a terminal from an MQTT topic. No need to ask why, just enjoy.