No, Userdoc doesn't provide API.
No, Userdoc doesn't provide mobile app.
Userdoc is located in
Userdoc offers Free Trial, Quotation Based, Subscription pricing models
Yes, Userdoc can integrate with Jira, monday.com, Asana, Pivotal Tracker and many more.You can find more integration for Userdoc here
The starting price is not disclosed by Userdoc. You can visit Userdoc pricing page to get the latest pricing.