When comparing VASSAL vs Roll20, the Slant community recommends VASSAL for most people. In the question“What are the best software tools for playing tabletop games over Internet?” VASSAL is ranked 3rd while Roll20 is ranked 4th. The most important reason people chose VASSAL is:
The source code is available [here](https://svn.code.sf.net/p/vassalengine/svn/), licensed under LGPL v2.1+.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Free and open source
The source code is available here, licensed under LGPL v2.1+.
Pro Tons of free game modules you can download
Pro A vast community that provides a great selection of games
Vassal engine allows downloading user pre-made games, called modules, from a public repository. There currently are over a 1.5k modules.
Pro Active develeopment
Vassal engine is actively maintained with a new release every other month or so.
Pro Cross-platform
VASSAL is available natively on Windows, OS X & Linux. See downloads page.
Pro There's nothing to download or install
Roll20 is a web-based application that can be run in any modern web-browser making for an easy and quick way to get all players up and running.
Pro Easy access to character sheets inside of RPGs
You can view your character sheets, and make rolls by clicking on various skills and abilities on the character sheet. You can cast spells by clicking on the appropriate parts of character sheets.
Pro Has a whole backlog of premade RPGs
Pro Free
It's free as long as you don't need too many features, otherwise you have to subscribe.
Pro Easy to control what players can see
With any subscription ($5/month) on the part of the GM, Dynamic Lighting can be enabled. This allows players to only be able to see what their characters should see, without any management by the GM. Light boundaries must be set up beforehand, or you can buy professional maps.
You can use fog of war for free, which has simple controls.
Pro Very easy to create 5e character sheets
Charactermancer uses SRD content, and any purchased modules to turn character creation into a multiple choice wizard. No need to type in the text of spells or abilities, the weights of objects, or calculate your armor class. This is all performed automatically.
Pro You can make whatever RPG you want
Pro Very easy prep for D&D 5e
Wizards has created purchasable modules for nearly every published fifth edition adventure. These are set up and ready to go, if you know how to use Roll20. There are additional 3rd party submissions available for purchase or for free on the marketplace.
Cons
Con No longer updated for newer versions of Java
Vassal doesn't support any versions of Java after version 8.
Con Laggy
The Roll20 interface is a little bit more sluggish than it ought to be.
Con Not 3D
Roll20 is a strictly 2D, top-down view tool.