Sign in with Klarna button allows customers to authenticate using Klarna credentials, reducing friction and pre-filling personal details at checkout. It also gives you access to user data for personalization. It is found in Homepage, Login and Register pages.

Account login	Account creation

The theme defines the button’s color. You can change the theme by setting the value of the theme attribute.

Apart from the default dark theme, you can apply the light theme to have the button displayed in white, or the outlined theme to render the white button with an outline.

Default theme (dark)

The button’s default theme color is dark. As the theme attribute is optional, the default theme is applied both when you set the attribute to default or if you omit it from the source code altogether. Don’t use default theme on black or dark backgrounds. The button must be used on backgrounds that provide sufficient contrast.

We recommend using the default theme as it’s widely recognized by Klarna customers and looks good on light backgrounds.

const siwkButton = klarna.Identity.button({
  scope: "openid offline_access payment:request:create profile:name",
  redirectUri: "http://localhost:3000/callback.html",
  theme: "default",
})

Light theme

Use the light theme to make the button visible on dark backgrounds. To apply the light theme, set the theme attribute to light. Don’t use light theme on white or light backgrounds. The button must be used on backgrounds that provide sufficient contrast.

const siwkButton = klarna.Identity.button({
  scope: "openid offline_access payment:request:create profile:name",
  redirectUri: "http://localhost:3000/callback.html",
  theme: "light",
})

Outlined theme

Use the outlined theme to make the button visible on all backgrounds. To apply the this theme, set the theme attribute to outlined. Don’t place on dark or saturated backgrounds. The button must be used on backgrounds that provide sufficient contrast.

const siwkButton = klarna.Identity.button({
  scope: "openid offline_access payment:request:create profile:name",
  redirectUri: "http://localhost:3000/callback.html",
  theme: "outlined",
})

Customizing the shape of the button to match your site's look and feel is a key step in creating a visually cohesive and engaging user experience. To control the button's shape, change the value of the shape attribute.

There are three shapes available with the Sign in with Klarna button: default, rectangular, and pill.

Rounded corners (default)

The default button shape is a rectangle with rounded corners. To apply the default shape, set the shape attribute of the element to default.

const siwkButton = klarna.Identity.button({
  scope: "openid offline_access payment:request:create profile:name",
  redirectUri: "http://localhost:3000/callback.html",
  shape: "default",
})

Minimum corner radius

To apply the rectangular shape with square corners, set the shape attribute of the element to rect.

const siwkButton = klarna.Identity.button({
  scope: "openid offline_access payment:request:create profile:name",
  redirectUri: "http://localhost:3000/callback.html",
  shape: "rect",
})

Maximum corner radius

To apply the pill shape, set the shape attribute of the element to pill.

const siwkButton = klarna.Identity.button({
  scope: "openid offline_access payment:request:create profile:name",
  redirectUri: "http://localhost:3000/callback.html",
  shape: "pill",
})

Width

Prominently display the Klarna button. Make the button the same width as other payment buttons in stacked button layouts.

​When width of button is blow 160px or the copy does not fit in the button, the text is removed and only the Klarna wordmark is shown.

​

Height

The default recommended height of the Klarna button is 48px and the min height allowed is 40px. Make sure the button is the same height of other payment buttons.

There are three ways you can choose to show the Klarna trademark on the button: badge, left icon or centered icon. These variants are available to make sure there is a button variant that is aligned with Partner's UI patterns. To control the button's alignment, change the value of the logoAlignment attribute.

Default

The default alignment is the Klarna badge centered with text before. To apply the default shape, set the logAlignment attribute of the Identity.button() function to default.

const siwkButton = klarna.Identity.button({
  scope: "openid offline_access payment:request:create profile:name",
  redirectUri: "http://localhost:3000/callback.html",
  logoAlignment: "default",
})

Left icon alignment

If you prefer to use the Klarna icon aligned to the left of the button, set the logoAlignment attribute of the Identity.button() function to left.

const siwkButton = klarna.Identity.button({
  scope: "openid offline_access payment:request:create profile:name",
  redirectUri: "http://localhost:3000/callback.html",
  logoAlignment: "left",
})

Centered icon alignment

If you prefer to position the Klarna icon to the center with the text trailing, set the logoAlignment attribute of the Identity.button() function to center.

const siwkButton = klarna.Identity.button({
  scope: "openid offline_access payment:request:create profile:name",
  redirectUri: "http://localhost:3000/callback.html",
  logoAlignment: "center",
})