I've been in the industry some time but here are some of my most hated software I've been forced to use:

• IBM Clearcase. Absolutely the worst dogshit source control system ever to exist. Complex, fragile, arcane, slow, network intensive. The company had to employ people fulltime on each of its sites whose only job was creating branches and mirroring repos on other sites. The operational & licensing costs of running it must be insane. Some defenders might claim "but it's so powerful!" or "look how we can create fancy layered views" as if that excuses it for being terrible in the most basic ways. Fixing it must have been intractable because IBM Clearcase eventually produced a faster remote client that talked to a proxy of the view running on a server somewhere. More expense and complexity.

• IBM/Lotus Notes & Domino. Another complex, arcane, slow, unintuitive, frustrating product by IBM (though owned by HCL now). Originally a content management system with an email / calendar with its own terminology and workflows completely divorced from any other email / calendar system in existence. Various iterations attempted to rework the front end to appear more user friendly but it was illusory - click button or two and you were confronted with dialogs that hadn't changed in 30 years.

• Internet Explorer. I've worked in company after company that had some really awful in-house expenses system or clock-in/clock-out or some enterprise junk that NEEDED Internet Explorer and no other browser would do because it was so badly written that it couldn't render properly or it used an ActiveX control.

• HP/Microfocus ALM. Another over-engineered, arcane, unintuitive piece of enterprise software. This time for tracking bugs, features, testing etc. Complicated and slow, heavily dependent on Internet Explorer and other deprecated Microsoft tech.

• Trend antivirus. Almost every corporate antivirus is bad but this one has been the bane of my existence. I write code which does stuff like encryption and compression/decompression and this piece of shit would constantly trigger warnings and delete binaries I was trying to build and develop. When it wasn't interfering with my work, it would just be constantly hogging CPU and slowing down disk activity.

• Enterprise software in general. This crap is sold like Kirby vacuum cleaners - a pushy salesman convinces a clueless CTO to buy junk that can seemingly do everything and a sign contract for $$$. And then this stuff is there FOREVER. Management will ignore complaints and the obvious shortcomings of the system because its paid for and the sunk cost fallacy kicks in.