Possible Field Types

Field	Description
bloks	Blocks: a field to interleave other components in your current one
text	Text: a text field
textarea	Textarea: a text area
richtext	Richtext: a richtext field
markdown	Markdown: write markdown with a text area and additional formatting options
number	Number: a number field
datetime	Date/Time: a date and time picker
boolean	Boolean: a checkbox - true/false
option	Single-Option: a single dropdown
options	Multi-Options: a list of checkboxes that allows multi-select
asset	Asset: Single asset (images, videos, audio, and documents)
multiasset	Multi-Assets: (images, videos, audio, and documents)
multilink	Link: an input field for adding links like internal linking to other stories, emails etc.
table	Table: a field for table format
section	Group: no input possibility - allows you to group fields in sections
custom	Plugin: Extend the editor yourself with a color picker or similar. Please take a look at Introduction to Field Plugins
image	Image (old): a upload field for a single image with cropping possibilities
file	File (old): a upload field for a single file

Example object

"field_key": {
 ...
 "type": "text", // <-- field type
 ...
}