Ktechlab might be a bit more popular than Altium Designer. We know about 1 link to it since March 2021 and only 1 link to Altium Designer. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.
Check out Altium’s website (altium.com. A lot of free resources that might help. They also have a YouTube channel. Good luck. Source: about 1 year ago
I found ktechlab and QUCS, both of them are Open Source. Source: almost 2 years ago
KiCad - A Cross Platform and Open Source Electronics Design Automation Suite
Proteus PCB design - Proteus PCB design combines the schematic capture and ARES PCB layout programs to provide a...
Autodesk EAGLE - Autodesk EAGLE is an electronic design automation (EDA) software.
Altium PCB Designer - Altium offers a top-notch, best-in-class PCB Designer to give engineers the tools they need to interlink with each side involved in the electronic design process.
EasyEDA - EasyEDA - Web-based EDA suite; runs in browser.
upverter - Upverter makes it easy to design and share electronics on the web.