---
id: api/utilities/blob
title: Cypress.Blob
description: Cypress automatically includes a Blob library and exposes it as Cypress.Blob.
section: api
source_path: docs/api/utilities/blob.mdx
version: 29f95bf8bb06f320986f3749f5bf09a35a409eab
updated_at: '2026-09-04T10:49:54.630Z'
---
# Cypress.Blob

Cypress automatically includes a [Blob](https://github.com/nolanlawson/blob-util) library and exposes it as `Cypress.Blob`.

Use `Cypress.Blob` to convert `base64` strings to Blob objects. Useful for testing uploads.

## Syntax

```
Cypress.Blob.method()
```

### Usage

**Correct Usage**

```
Cypress.Blob.method()
```

**Incorrect Usage**

```
cy.Blob.method() // Errors, cannot be chained off 'cy'
```

## Examples

### Image Fixture

#### Using an image fixture for jQuery plugin upload

```
// programmatically upload the logo
cy.fixture('images/logo.png').as('logo')
cy.get('input[type=file]').then(function ($input) {
  // convert the logo base64 string to a blob
  const blob = Cypress.Blob.base64StringToBlob(this.logo, 'image/png')

  // pass the blob to the fileupload jQuery plugin
  // https://github.com/blueimp/jQuery-File-Upload
  // used in your application's code
  // which initiates a programmatic upload
  $input.fileupload('add', { files: blob })
})
```

### Getting dataUrl string

#### Create an `img` element and set its `src` to the `dataUrl`

```
return Cypress.Blob.imgSrcToDataURL('/assets/img/logo.png').then((dataUrl) => {
  const img = Cypress.$('<img />', { src: dataUrl })

  cy.get('.utility-blob').then(($div) => {
    // append the image
    $div.append(img)
  })
  cy.get('.utility-blob img').click().should('have.attr', 'src', dataUrl)
})
```

## History

| Version | Changes |
| --- | --- |
| [5.0.0](/llm/markdown/app/references/changelog.md) | Return type of `arrayBufferToBlob`, `base64StringToBlob`, `binaryStringToBlob`, and `dataURLToBlob` methods changed from `Promise<Blob>` to `Blob` |
| [5.0.0](/llm/markdown/app/references/changelog.md) | Added `arrayBufferToBinaryString`, `binaryStringToArrayBuffer` methods. |

## See also

*   [Bundled Libraries](/llm/markdown/app/references/bundled-libraries.md)