Cheers! User does not replace project management tools like Jira, in fact they work together. Where Jira is about planning and implementation (who does what, when, hows it's progressing etc) - it's not a great place to keep requirements, especially as your source of truth.

So where Userdoc comes in is.. 1. The requirements gathering phase (e.g. work with your clients or team) 2. The requirements sign-off phase (get clients to approve the requirements) 3. Sync all requirements into Jira, Asana, Trello - 1000's of other platforms. 4. Testing - you can export documents of all the stories and AC's easily 5. Changes - instead of making new stories for changes, alter the existing AC, and sync 6. Long-term documentation - don't lost your requirements after the sprint ends