ImageKit.io JavaScript SDK

A lightweight JavaScript SDK for generating image and video URLs with transformations, and for uploading files directly from the browser to ImageKit. This SDK is intended for use in the browser only. For Node.js, please refer to our official Node.js SDK.

Table of Contents

• Installation
• Initialization
• URL Generation
  • Basic URL Generation
  • Advanced URL Generation Examples
    • Chained Transformations
    • Overlays and Effects
    • AI and Advanced Transformations
    • Arithmetic Expressions in Transformations
  • Supported Transformations
  • Handling Unsupported Transformations
• File Upload
  • Basic Upload Example
  • Promise-based Upload Example
• Test Examples
• Changelog

Installation

Using npm

Install the SDK via npm:

npm install imagekit-javascript --save
# or
yarn add imagekit-javascript

Then import ImageKit:

import ImageKit from "imagekit-javascript";
// or with CommonJS:
const ImageKit = require("imagekit-javascript");

Using CDN

You can also use the global CDN:

Download a specific version:

https://unpkg.com/imagekit-javascript@1.3.0/dist/imagekit.min.js

Or for the latest version, remove the version number (don't use in production as it may break your code if a new major version is released):

https://unpkg.com/imagekit-javascript/dist/imagekit.min.js

And include it in your HTML:

<script type="text/javascript" src="https://unpkg.com/imagekit-javascript/dist/imagekit.min.js"></script>

Initialization

To use the SDK, initialize it with your ImageKit URL endpoint. You can get the URL endpoint here and your public API key from the developer section:

var imagekit = new ImageKit({
    urlEndpoint: "https://ik.imagekit.io/your_imagekit_id", // Required
    transformationPosition: "query", // Optional, defaults to "query"
    publicKey: "your_public_api_key", // Optional, required only for client-side file uploads
});

Note: Never include your private API key in client-side code. The SDK will throw an error if you do.

Initialization Options

Option	Description	Example
urlEndpoint	Required. Your ImageKit URL endpoint or custom domain.	urlEndpoint: "https://ik.imagekit.io/your_id"
transformationPosition	Optional. Specifies whether transformations are added as URL path segments (path) or query parameters (query). The default is query, which allows you to perform wildcard purges and remove all generated transformations from the CDN cache.	transformationPosition: "query"
publicKey	Optional. Your public API key for client-side uploads.	publicKey: "your_public_api_key"

URL Generation

The SDK’s .url() method enables you to generate optimized image and video URLs with a variety of transformations.

The method accepts an object with the following parameters:

Option	Description	Example
path	The relative path of the image. Either src or path must be provided.	"/path/to/image.jpg"
src	The full URL of an image already mapped to ImageKit. Either src or path must be provided.	"https://ik.imagekit.io/your_imagekit_id/path/to/image.jpg"
transformation	An array of objects specifying the transformations to be applied in the URL. Each object contains key-value pairs representing transformation parameters. See supported transformations.	[ { width: 300, height: 400 } ]
queryParameters	Additional query parameters to be appended to the URL.	{ v: 1 }

Optionally, you can include transformationPosition and urlEndpoint in the object to override the initialization settings for a specific .url() call.

Basic URL Generation

A simple height and width transformation:

var imageURL = imagekit.url({
    path: "/default-image.jpg",
    urlEndpoint: "https://ik.imagekit.io/your_imagekit_id/endpoint/",
    transformation: [{
        height: 300,
        width: 400
    }]
});

Result Example:

https://ik.imagekit.io/your_imagekit_id/endpoint/default-image.jpg?tr=h-300,w-400

SDK automatically generates the URL based on the provided parameters. The generated URL includes the base URL, path, and transformation parameters.

Advanced URL Generation Examples

Chained Transformations

Apply multiple transformations by passing an array:

var imageURL = imagekit.url({
    path: "/default-image.jpg",
    transformation: [{
        height: 300,
        width: 400
    }, {
        rotation: 90
    }],
});

Result Example:

https://ik.imagekit.io/your_imagekit_id/default-image.jpg?tr=h-300,w-400:rt-90

Overlays and Effects

Text Overlay Example:

var imageURL = imagekit.url({
    src: "https://ik.imagekit.io/your_imagekit_id/default-image.jpg",
    transformation: [{
        width: 400,
        height: 300,
        overlay: {
            text: "Imagekit",
            fontSize: 50,
            color: "red",
            position: {
                x: 10,
                y: 20
            }
        }
    }]
});

Image Overlay Example:

var imageURL = imagekit.url({
    src: "https://ik.imagekit.io/your_imagekit_id/default-image.jpg",
    transformation: [{
        width: 400,
        height: 300,
        overlay: {
            type: "image",
            input: "logo.png",
            transformation: [{
                width: 100,
                border: "10_CDDC39"
            }],
            position: {
                focus: "top_left"
            }
        }
    }]
});

Video Overlay Example:

var videoOverlayURL = imagekit.url({
    src: "https://ik.imagekit.io/your_imagekit_id/base-video.mp4",
    transformation: [{
        overlay: {
            type: "video",
            input: "overlay-video.mp4",
            position: { 
                x: "10", 
                y: "20" 
            },
            timing: { 
                start: 5, 
                duration: 10 
            }
        }
    }]
});

Subtitle Overlay Example:

var subtitleOverlayURL = imagekit.url({
    src: "https://ik.imagekit.io/your_imagekit_id/base-video.mp4",
    transformation: [{
        overlay: {
            type: "subtitle",
            input: "subtitle.vtt",
            transformation: [{
                fontSize: 16,
                fontFamily: "Arial"
            }],
            position: { 
                focus: "bottom" 
            },
            timing: { 
                start: 0, 
                duration: 5 
            }
        }
    }]
});

Solid Color Overlay Example:

var solidColorOverlayURL = imagekit.url({
    src: "https://ik.imagekit.io/your_imagekit_id/base-image.jpg",
    transformation: [{
        overlay: {
            type: "solidColor",
            color: "FF0000",
            transformation: [{
                width: 100,
                height: 50,
                alpha: 5
            }],
            position: { x: 20, y: 20 }
        }
    }]
});

Overlay Options

ImageKit supports various overlay types, including text, image, video, subtitle, and solid color overlays. Each overlay type has specific configuration options to customize the overlay appearance and behavior. To learn more about how overlays work, refer to the ImageKit documentation.

The table below outlines the available overlay configuration options:

Option	Description	Example
type	Specifies the type of overlay. Supported values: text, image, video, subtitle, solidColor.	type: "text"
text	(For text overlays) The text content to display.	text: "ImageKit"
input	(For image, video, or subtitle overlays) Relative path to the overlay asset.	input: "logo.png" or input: "overlay-video.mp4"
color	(For solidColor overlays) RGB/RGBA hex code or color name for the overlay color.	color: "FF0000"
encoding	Accepted values: auto, plain, base64. Check this for more details.	encoding: "auto"
transformation	An array of transformation objects to style the overlay. - Text Overlay Transformations - Subtitle Overlay Transformations - Image and video overlays support most transformations. See ImageKit docs for more details.	transformation: [{ fontSize: 50 }]
position	Sets the overlay’s position relative to the base asset. Accepts an object with x, y, or focus. The focus value can be one of: center, top, left, bottom, right, top_left, top_right, bottom_left, or bottom_right.	position: { x: 10, y: 20 } or position: { focus: "center" }
timing	(For video base) Specifies when the overlay appears using start, duration, and end (in seconds); if both duration and end are set, duration is ignored.	timing: { start: 5, duration: 10 }

Encoding Options

Overlay encoding options define how the overlay input is converted for URL construction. When set to auto, the SDK automatically determines whether to use plain text or Base64 encoding based on the input content.

For text overlays:

• If auto is used, the SDK checks the text overlay input: if it is URL-safe, it uses the format i-{input} (plain text); otherwise, it applies Base64 encoding with the format ie-{base64_encoded_input}.
• You can force a specific method by setting encoding to plain (always use i-{input}) or base64 (always use ie-{base64}).
• Note: In all cases, the text is percent-encoded to ensure URL safety.

For image, video, and subtitle overlays:

• The input path is processed by removing any leading/trailing slashes and replacing inner slashes with @@ when plain is used.
• Similarly, if auto is used, the SDK determines whether to apply plain text or Base64 encoding based on the characters present.
• For explicit behavior, use plain or base64 to enforce the desired encoding.

Use auto for most cases to let the SDK optimize encoding, and use plain or base64 when a specific encoding method is required.

Solid Color Overlay Transformations

Option	Description	Example
width	Specifies the width of the solid color overlay block (in pixels or as an arithmetic expression).	width: 100
height	Specifies the height of the solid color overlay block (in pixels or as an arithmetic expression).	height: 50
radius	Specifies the corner radius of the solid color overlay block or shape. Can be a number or "max" for circular/oval shapes.	radius: "max"
alpha	Specifies the transparency level of the solid color overlay. Supports integers from 1 (most transparent) to 9 (least transparent).	alpha: 5

Text Overlay Transformations

Option	Description	Example
width	Specifies the maximum width (in pixels) of the overlaid text. The text wraps automatically, and arithmetic expressions are supported (e.g., bw_mul_0.2 or bh_div_2).	width: 400
fontSize	Specifies the font size of the overlaid text. Accepts a numeric value or an arithmetic expression.	fontSize: 50
fontFamily	Specifies the font family of the overlaid text. Choose from the supported fonts or provide a custom font.	fontFamily: "Arial"
fontColor	Specifies the font color of the overlaid text. Accepts an RGB hex code, an RGBA code, or a standard color name.	fontColor: "FF0000"
innerAlignment	Specifies the inner alignment of the text when it doesn’t occupy the full width. Supported values: left, right, center.	innerAlignment: "center"
padding	Specifies the padding around the text overlay. Can be a single integer or multiple values separated by underscores; arithmetic expressions are accepted.	padding: 10
alpha	Specifies the transparency level of the text overlay. Accepts an integer between 1 and 9.	alpha: 5
typography	Specifies the typography style of the text. Supported values: b for bold, i for italics, and b_i for bold with italics.	typography: "b"
background	Specifies the background color of the text overlay. Accepts an RGB hex code, an RGBA code, or a color name.	background: "red"
radius	Specifies the corner radius of the text overlay. Accepts a numeric value or max for circular/oval shape.	radius: "max"
rotation	Specifies the rotation angle of the text overlay. Accepts a numeric value for clockwise rotation or a string prefixed with N for counterclockwise rotation.	rotation: 90
flip	Specifies the flip option for the text overlay. Supported values: h, v, h_v, v_h.	flip: "h"
lineHeight	Specifies the line height for multi-line text. Accepts a numeric value or an arithmetic expression.	lineHeight: 1.5

Subtitle Overlay Transformations

Option	Description	Example
background	Specifies the subtitle background color using a standard color name, RGB color code, or RGBA color code.	background: "blue"
fontSize	Sets the font size of subtitle text.	fontSize: 16
fontFamily	Sets the font family of subtitle text.	fontFamily: "Arial"
color	Specifies the font color of subtitle text using standard color name, RGB, or RGBA color code.	color: "FF0000"
typography	Sets the typography style of subtitle text. Supported values: b, i, b_i.	typography: "b"
fontOutline	Specifies the font outline for subtitles. Requires an outline width and color separated by an underscore.	fontOutline: "2_blue"
fontShadow	Specifies the font shadow for subtitles. Requires shadow color and indent separated by an underscore.	fontShadow: "blue_2"

AI and Advanced Transformations

Background Removal:

var imageURL = imagekit.url({
  path: "/sample-image.jpg",
  transformation: [{
    aiRemoveBackground: true
  }]
});

Upscaling:

var upscaledURL = imagekit.url({
  path: "/sample-image.jpg",
  transformation: [{
    aiUpscale: true
  }]
});

Drop Shadow:

var dropShadowURL = imagekit.url({
  path: "/sample-image.jpg",
  transformation: [{
    aiDropShadow: "az-45"
  }]
});

Arithmetic Expressions in Transformations

var imageURL = imagekit.url({
    src: "https://ik.imagekit.io/your_imagekit_id/default-image.jpg",
    transformation: [{
        width: "iw_div_4",
        height: "ih_div_2",
        border: "cw_mul_0.05_yellow"
    }]
});

Supported Transformations

The SDK gives a name to each transformation parameter (e.g. height maps to h, width maps to w). If the property does not match any of the following supported options, it is added as is.

If you want to generate transformations without any modifications, use the raw parameter.

Check ImageKit transformation documentation for more details.

Transformation Name	URL Parameter
width	w
height	h
aspectRatio	ar
quality	q
aiRemoveBackground	e-bgremove (ImageKit powered)
aiRemoveBackgroundExternal	e-removedotbg (Using third party)
aiUpscale	e-upscale
aiRetouch	e-retouch
aiVariation	e-genvar
aiDropShadow	e-dropshadow
aiChangeBackground	e-changebg
crop	c
cropMode	cm
x	x
y	y
xCenter	xc
yCenter	yc
focus	fo
format	f
radius	r
background	bg
border	b
rotation	rt
blur	bl
named	n
dpr	dpr
progressive	pr
lossless	lo
trim	t
metadata	md
colorProfile	cp
defaultImage	di
original	orig
videoCodec	vc
audioCodec	ac
grayscale	e-grayscale
contrastStretch	e-contrast
shadow	e-shadow
sharpen	e-sharpen
unsharpMask	e-usm
gradient	e-gradient
flip	fl
opacity	o
zoom	z
page	pg
startOffset	so
endOffset	eo
duration	du
streamingResolutions	sr
overlay	Generates the correct layer syntax for image, video, text, subtitle, and solid color overlays.
raw	The string provided in raw will be added in the URL as is.

Handling Unsupported Transformations

If you specify a transformation parameter that is not explicitly supported by the SDK, it is added “as-is” in the generated URL. This provides flexibility for using new or custom transformations without waiting for an SDK update.

For example:

var imageURL = imagekit.url({
    path: "/test_path.jpg",
    transformation: [{
        newparam: "cool"
    }]
});
// Generated URL: https://ik.imagekit.io/test_url_endpoint/test_path.jpg?tr=newparam-cool

File Upload

The SDK offers a simple interface via the .upload() method to upload files to the ImageKit Media Library. This method requires the following:

• file (mandatory)
• fileName (mandatory)
• Security parameters: signature, token, and expire

Before invoking the upload, generate the necessary security parameters as per the ImageKit Upload API documentation.

Upload Options

Option	Description	Example
file	The file content to be uploaded. Accepts binary, base64 string, or URL.	file: fileInput.files[0]
fileName	The name to assign to the uploaded file. Supports alphanumeric characters, dot, underscore, and dash.	fileName: "myImage.jpg"
signature	HMAC-SHA1 digest computed using the private API key. Must be calculated on the server side.	signature: "generated_signature"
token	A unique token to prevent duplicate upload retries. Typically a V4 UUID or similar unique string.	token: "unique_upload_token"
expire	Unix timestamp (in seconds) indicating the signature expiry time (should be within 1 hour).	expire: 1616161616
useUniqueFileName	Boolean flag to automatically generate a unique filename if set to true. Defaults to true.	useUniqueFileName: true
folder	The folder path where the file will be uploaded. Automatically creates nested folders if they don’t exist.	folder: "/images/uploads"
isPrivateFile	Boolean to mark the file as private, restricting access to the original file URL. Defaults to false.	isPrivateFile: false
tags	Tags to associate with the file. Can be a comma-separated string or an array of tags.	tags: "summer,holiday" or tags: ["summer","holiday"]
customCoordinates	Specifies an area of interest in the image formatted as x,y,width,height.	customCoordinates: "10,10,100,100"
responseFields	Comma-separated list of fields to include in the upload response.	responseFields: "tags,customCoordinates"
extensions	Array of extension objects for additional image processing.	extensions: [{ name: "auto-tagging" }]
webhookUrl	URL to which the final status of extension processing will be sent.	webhookUrl: "https://example.com/webhook"
overwriteFile	Boolean flag indicating whether to overwrite a file if it exists. Defaults to true.	overwriteFile: true
overwriteAITags	Boolean flag to remove AITags from a file if overwritten. Defaults to true.	overwriteAITags: true
overwriteTags	Boolean flag that determines if existing tags should be removed when new tags are not provided. Defaults to true when file is overwritten without tags.	overwriteTags: true
overwriteCustomMetadata	Boolean flag dictating if existing custom metadata should be removed when not provided. Defaults to true under similar conditions as tags.	overwriteCustomMetadata: true
customMetadata	Stringified JSON or an object containing custom metadata key-value pairs to associate with the file.	customMetadata: {author: "John Doe"}
transformation	Optional transformation object to apply during the upload process. It follows the same structure as in URL generation.	transformation: { pre: "w-200,h-200", post: [...] }
xhr	An optional XMLHttpRequest object provided to monitor upload progress.	xhr: new XMLHttpRequest()
checks	Optional string value for specifying server-side checks to run before file upload.	checks: "file.size' < '1MB'"

Basic Upload Example

Below is an HTML form example that uses a callback for handling the upload response:

<form action="#" onsubmit="upload(); return false;">
    <input type="file" id="file1" />
    <input type="submit" />
</form>
<script src="../dist/imagekit.js"></script>
<script>
    var imagekit = new ImageKit({
        publicKey: "your_public_api_key",
        urlEndpoint: "https://ik.imagekit.io/your_imagekit_id",
    });
    
    function upload() {
        var file = document.getElementById("file1");
        imagekit.upload({
            file: file.files[0],
            fileName: "abc1.jpg",
            token: 'generated_token',
            signature: 'generated_signature',
            expire: 'generated_expire'
        }, function(err, result) {
            if(err){
                console.error(err);
            } else {
                console.log(result);
            }
        });
    }
</script>

Promise-based Upload Example

You can also use promises for a cleaner asynchronous approach:

imagekit.upload({
    file: file.files[0],
    fileName: "abc1.jpg",
    token: 'generated_token',
    signature: 'generated_signature',
    expire: 'generated_expire'
}).then(result => {
    console.log(result);
}).catch(error => {
    console.error(error);
});

Test Examples

For a quick demonstration of the SDK features, check the test suite:

• URL generation examples can be found in basic.js and overlay.js files.
• File upload examples can be found in test/upload.js.

Changelog

For a detailed history of changes, please refer to CHANGELOG.md.