Cuelark is a web-based platform that provides a collection of free tools for image conversion, PDF manipulation, and developer tasks. The primary function of the service is to allow users to convert and compress image files, merge and split PDFs, and generate cron expressions directly within their browser. A key technical feature is that all file processing occurs locally on the user's device, meaning files are not uploaded to an external server. No user account or sign-up is required to access the tools. The image tools support conversion between HEIC, WebP, AVIF, JPG, and PNG formats. Users can also compress photos to a specific target size, such as 100 KB or less. The PDF tools enable merging multiple documents into a single file, splitting a document into separate pages, and rearranging page order. For developers, Cuelark offers a cron expression builder and other small utilities intended for everyday operational work. Typical use cases include converting HEIC images from iOS devices to the more widely compatible JPG or PNG formats, compressing WebP or AVIF images for web optimization, and combining or splitting PDFs without relying on server-based software. The platform includes guides that provide transparency into the conversion and compression process, detailing how files are affected based on real-world testing. The workflow involves selecting the desired tool, choosing a file from the local device, and downloading the processed result. The tools are maintained by the Cuelark Team and are accessible at tools.cuelark.com.