CaseFu.com - Write great FS easily

Create interactive mockups of the UI: the screens, navigation between them, and the forms, fields, tables and action buttons.
Let the reader see the UI visually and navigate it interactively. To understand what the future application will do, there is nothing like actually clicking through the screens of it, the screen visual is worth a thousand words of description.
Focus on system functionality. CaseFu lets you create functionality-focused screen mockups very easily, thus enabling you to skip aspects that are irrelevant in a functional specification, such as the UI look and feel and the screen layout.

Specify the application's data model: the entities, relations between them, entity attributes and their data types.
Logical and physical. Support for relations cardinality and foreign keys.

Write system's use cases. Have a standard, clear and comprehensive documentation of the system functionality, including actors and use cases with main success scenario and extensions.
Fill in the spec into screen mockups. When a formal use case is an overkill, add a quick description directly to screens, action buttons and fields.

Simple and easy. Create the whole functional specification in a super-simple plain-text format based on Markdown. Anyone can do it.
Search, replace, copy. Naturally. Reap all the benefits of working with plain text when writing your functional specification.
Version your FSD in Git. Or in any other VCS of your choice. Create release versions and keep them in sync with the application itself.

Prototype a screen literally in 1 minute. Hold an interactive session with your stakeholders and let them see new screens emerge in real-time right before their eyes! How cool it that?

Single, self-contained HTML file: let the readers read it on-line on Github, download it or just send it out to them via e-mail.
Everything's connected. Navigate the whole FSD via HTML links, from screen mockup to use case to data model - and back.
No broken links - guaranteed. References between items are verified by the tool, so you won't have any broken links in the FSD, ever.
Full-text search. Search for items containing a given phrase in full-text easily.
Print mode. Show the whole of the FSD in the browser window at once to print it.

Create great Functional Specification easily