Web developers often face challenges when converting data formats, such as transforming a base64 string into a blob using JavaScript, particularly when APIs require data in specific formats like blobs for images. A blob is a binary data representation that can be used for files, images, or videos. The Fetch API, a feature in web browsers, simplifies this conversion by enabling the retrieval of resources across a network and returning them in various formats, including blobs. By passing a base64 string to the Fetch API and converting the response to a blob, developers can easily upload or display images. Conversely, converting a blob back to a base64 string is more complex and can be achieved using a Promise and the FileReader API. This process was practically applied in a demo app where photos of receipts were taken, requiring conversion for permanent storage. These modern techniques streamline data manipulation, making them less daunting for developers.