Customizing theme using query parameters | Transak

Use Transak’s theme-related query parameters in widgetParams to customize button colors, color mode, and the full widget theme.

Pass these parameters in the Create Widget URL API request body when generating a widgetUrl.

apiKey and referrerDomain are mandatory in widgetParams for all examples on this page.

Primary Button Colors

Use these parameters to customize the primary button background and text color.

Parameter	Description
`primaryButtonFillColor`	Hex color for the button background
`primaryButtonTextColor`	Hex color for the button text

Sample Result

Primary CTA button restyled to match brand mustard and dark grey text using primaryButtonFillColor and primaryButtonTextColor.

Primary button color customization example

Sample Request

$ curl --request POST \
>   --url https://api-gateway-stg.transak.com/api/v2/auth/session \
>   --header 'accept: application/json' \
>   --header 'access-token: YOUR_ACCESS_TOKEN' \
>   --header 'content-type: application/json' \
>   --data '{
>     "widgetParams": {
>       "apiKey": "YOUR_API_KEY",
>       "referrerDomain": "yourdomain.com",
>       "primaryButtonFillColor": "#F59E0B",
>       "primaryButtonTextColor": "#0B0B0B"
>     }
>   }'

Color Mode

Use colorMode to switch the widget between light and dark themes.

Parameter	Allowed values	Description
`colorMode`	`LIGHT`, `DARK`	Sets the widget theme mode

Sample Result

Sample Request

$ curl --request POST \
>   --url https://api-gateway-stg.transak.com/api/v2/auth/session \
>   --header 'accept: application/json' \
>   --header 'access-token: YOUR_ACCESS_TOKEN' \
>   --header 'content-type: application/json' \
>   --data '{
>     "widgetParams": {
>       "apiKey": "YOUR_API_KEY",
>       "referrerDomain": "yourdomain.com",
>       "colorMode": "DARK"
>     }
>   }'

Complete Theme Customization

Use the following parameters together to fully align the widget with your brand.

Brand and Text Colors

Parameter	Description
`brandColor`	Primary brand color for accents and links
`textPrimaryColor`	Primary text color
`textSecondaryColor`	Secondary or muted text color
`labelTextColor`	Form label text color

Surface and Background Colors

Parameter	Description
`surfaceFillColor`	Card or surface background
`widgetBackgroundFillColor`	Widget container background
`borderColor`	Border color for inputs and cards

Status Colors

Parameter	Description	Example value
`greenColor`	Success or positive state	`#10B981`
`redColor`	Error or negative state	`#EF4444`

Putting It All Together

Below is an example combining color mode, primary button styling, and full theme customization into a single widget URL flow.

Sample Result

Sample Request

$ curl --request POST \
>   --url https://api-gateway-stg.transak.com/api/v2/auth/session \
>   --header 'accept: application/json' \
>   --header 'access-token: YOUR_ACCESS_TOKEN' \
>   --header 'content-type: application/json' \
>   --data '{
>     "widgetParams": {
>       "apiKey": "YOUR_API_KEY",
>       "referrerDomain": "yourdomain.com",
>       "brandColor": "#F6DC2D",
>       "textPrimaryColor": "#FFFFFF",
>       "textSecondaryColor": "#8F8F8F",
>       "labelTextColor": "#FFFFFF",
>       "surfaceFillColor": "#452167",
>       "widgetBackgroundFillColor": "#300856",
>       "borderColor": "#6A4D85",
>       "greenColor": "#34D399",
>       "redColor": "#EF4444"
>     }
>   }'