Is free version available in SharePoint 2016

Until SharePoint 2013, there was a SharePoint foundation version available, which is free. Unfortunately in SharePoint 2016 it is deprecated.

What's deprecated or removed from SharePoint Server 2016

But still if you want to try out SharePoint 2016, you can use SharePoint 2016 trial .

You can use one of the following trial product keys. The trial period is 180 days.

• Enterprise trial product key: NQGJR-63HC8-XCRQH-MYVCH-3J3QR
• Standard trial product key: RTNGH-MQRV6-M3BWQ-DB748-VH7DM

Please note

1. You can not extend trial period for SharePoint
2. You can convert to a licensed installation at any time during the trial or after the trial has expired by entering the appropriate product key in Central Administration.
3. If your company have MSDN subscription, you will able to use SharePoint free for development purpose, but you can't use it in Production environment.

Hope this helps!!!