When comparing Draw.io vs Affinity Designer, the Slant community recommends Draw.io for most people. In the question“What are the best mockup and wireframing tools for websites?” Draw.io is ranked 4th while Affinity Designer is ranked 17th.
Ranked in these QuestionsQuestion Ranking
Pro Rich functionality for a web-based application
Pro Completely free
Pro Integrates with multiple cloud storage services
Draw.io offers saving files directly to services such as Google Drive, OneDrive or Dropbox along with saving to to computer.
Pro There is also a Desktop version
Pro Good list of different output formats
Draw.io supports export for PNG, GIF, JPEG, PDF, SVG, HTML, and XML.
Pro Internet Explorer 6-8 and touch device support
Draw.io works with every browser (even IE 6) without plugins.
Pro Real-time collaboration
Pro One-time purchase
Rather than a monthly subscription based model, Affinity Designer instead has a one-time fee ($49.99).
Pro Intuitive user interface
The user interface of many graphic editing software programs can often be discouraging for beginners. Affinity Designer, however, has a very well laid out and intuitive user interface with a small learning curve.
Pro Powerful artistic tools
Extensively tweakable brush types, color options...
Pro Sketch Alternative (Great for Mixed OS Teams)
For those working in mixed environments that aren't 100% MacOS, you'll find devoting yourself to Sketch.app brings with it...pain. If this fits the bill for what you need feature-wise and you're in a mixed OS environment, it's a very capable replacement for Sketch.app. Note that it doesn't have all the same features, but then again it doesn't need all the same features. Short of organization differences inside the document you're working on, there shouldn't be anything you can't do with Affinity Designer that you could have with Sketch.
Pro Extended slicing and export possibilities
An object can easily be transformed into a slice that can then be exported in various sizes end formats in 1 go. E.g. Export slice A as PNG 1x, 2x and 3x AND GIF 1x AND SVG.
Pro Powerful symbol managemment
Symbols can get individual property changes (color, shape, layer effects, fonts text...) while the other properties stay linked with the base symbol.
Pro SVG Support
In the era of "retina" displays, 4k UHD, 5k, and even 8k, Scalar Vector Graphics - independent vector images that can scale to any resolution without any display quality loss - are more important now than ever.
And this tool is quite capable of rendering true SVG output suitable for consumption at any display resolution (not a big bunch of rasterized bits in the document, actual paths, points, etc.).
Pro Cross platform
Available on both Windows and MacOS
Pro Focused vector graphics tool
Unlike some design tools, Affinity Designer isn't trying to be all things to all people. It's focused on its main area of expertise: vector graphics. That's not to say you can't use a raster image (think a photo in *.jpeg format for example), but it's not built to do much with that other than using it somewhere amidst the layers and that's about it.
Pro Integrates well with Affinity Photo
These are companion apps & switching between them is built in - Photo is a very powerful raster tool with a feature set close/better to Photoshop, it will also use some Photoshop plugins. This allows you to add-on powerful raster capabilities if you want them - put doesn't force you to.
Pro Excellent Photoshop/Illustrator import & export
Best I have seen in a non Adobe app, you can use most of the Photoshop mock-ups and templates easily. Opens most Adobe files to a level to be able to effectively use the content. Allows cross team collaboration across tool-chains.
The new version 1.5 has a very powerful feature set such as support for symbols and asset windows, as well as constraints controls and improved export options. This all adds up to an interesting alternative to Adobe Illustrator.
Con Behaves strangely for certain diagram types
For example the snapping function for arrows doesn't work properly for the sequence diagram template
Con Import from Visio .vsd is useless
I opened a simple diagram and it's all scattered.
Con No plug-in architecture, so can't be tailored to specific purposes
Some applications (e.g. Sketch) have an open plug-in framework, by which the software can be extended by independent/third-party developers according to popular trends.
Con Treats all objects as filled
You can't select objects on the canvas by clicking on them, if they're surrounded by another object (like a rectangle or a frame). Designer treats all objects as filled, so if you've drawn a frame or outline or an object with a hole in it, you can't select objects within that hole directly. You have to laboriously iterate through all objects in a list until you get to the one you want. This is an extremely common situation, which cripples the entire product. Very surprising and unfortunate defect.