What are some alternatives?
When comparing Ultradox and Pics.io Design, you can also consider the following products
Kofax - Kofax software provides information capture, process management, data integration, customer communications management and analytics.
Cornerstone 4 by Assembla - The ultimate Subversion client for Mac
S-Docs - S-Docs is an add-on that generates quotes, contracts, invoices, reports and any other document directly on Salesforce.
Folio for Mac - Simple version control app for designers
Windward Studios - Windward's solution includes a .NET or Java Engine, a set of code libraries for integrating reporting and document generation.
Zeplin - Collaboration app for UI designers & frontend developers