Background:
We have at work an internal bug tracking system based on a heavily customized TFS (aka azure devops) template, with an internal workflow against QA and customers. Both the template and the workflow were partially developed by me, and partially by my managers over the years.

Many of the posts here echo my own experiences / grievances.

My own wish list:

* Issues should be integrated into git – like @BiteCode_dev asked for above [0]. One of the big advantages of TFS is the tight integration between issues and source control. But the disadvantage is the central server, which isn't available off premises in locked-down systems. In other words, the bug tracker should load all of its data from the repo, with potential pointers given to external big resources like screenshots, dumps, etc. Should have an easy way to pick a commit and associate it with the fixed bug.

* No push notifications. For the same reasons like @BiteCode_dev detailed above. Emails are fine.

* An API that allows building a simple web interface for users to submit bug reports, including a sample page that can be easily customized, with examples on how to auto-fill some of the fields. We have something like that, and it works great. When the app crashes users are immediately taken to this page and it auto-fills for them the type of the bug, their username, a stack trace, screenshot, and a link to the dump file (saved separately).

* Everything @q3k said above[1]. The fast interface, fast search, rich search (according to categories), the flat space of issue IDs (which TFS has and they work great), the customizability of category/component (which TFS also has), the API for automation (ditto for TFS). In fact I will only consider a bug tracking system if it has all those features.

* No pre-defined flows for open->closed, but an ability to define your own. Allow different flows for different type of issues – e.g. requirements vs. bugs.

* An easy way to copy an existing bug and all its fields to a new bug.

* A customizable way to categorize all bugs in order of importance. We have our own way of doing it, using a formula that takes into account the reporter (QA or users or managers or developer), the severity of the bug (crash vs. minor ux issues), the commonness of the bug (how many users encountered it), the estimated time to fix the bug, and the impact of the code change (a fix in a fundamental library vs a ux only tweak). This is helping a lot with prioritization when there are thousands of bugs. This can of course be customized since it's different for every team and every product.

* Can be used offline and on-premise.

* An easy API to migrate issues from other legacy system. Jira, TFS, etc.

* Standard keyboard navigation. E.g. on Windows: tabbing between fields, ctrl+s to save the changes, ctrl+z to undo edits on current field.

* Conversations and mentions with time-tags.

* A seamless way to add attachments, and to automatically store them in the correct location: small attachments (stack traces, other txt files) can be added directly to the repo. Big attachments (dumps, large screenshots, etc) should automatically be thrown in a pre-defined location – network share for an on-premise deployment, or Google Drive / OneDrive etc. I waste a couple of annoying minutes myself each week doing this for customer complaints.

* An easy API that allows integration into project management systems, for PMs.

As for your website:

* Like @chx31 said above, the cute animations are a turn off. If you want to sell this to experienced developers, this raises red flags.

* The use of the word "modern" in your website is another red flag. It's an empty, vacuous adjective that means to me you have no actual features and can't even describe your own system without insulting older systems. It's also somewhat ageist, as if you mean to imply older systems suck, or older developers suck. It's a huge turnoff for me whenever I see it on every landing page, sorry. And if you didn't mean to insult anyone then the word "modern" still has no meaning.

[0] https://news.ycombinator.com/item?id=26912758

[1] https://news.ycombinator.com/item?id=26912858