ToolBench is a free online image converter that runs entirely in the browser, emphasizing privacy and local processing: files are read and written only by the user's own browser and are not sent to a server, so there is no uploading, no registration, no file size or file quantity limits, and it can continue to be used even if the network is disconnected after the page loads.
In terms of main capabilities, it supports input in formats such as JPG, PNG, WebP, AVIF, GIF, BMP, TIFF, and ICO, and can output to JPG, PNG, WebP, AVIF, GIF, BMP, TIFF, ICO, and PDF. Conversion supports per-file control, allowing different output formats to be selected for different images in a single batch process. Quality can be adjusted individually for each file, and proportional scaling by maximum width is supported during conversion; for formats that do not support an alpha channel, transparent areas are filled with a white background instead of the black edges defaulted to by some converters.
Usage is as follows: click Choose Files to select the images to convert; set the output format for each file, and click the gear icon when quality or dimensions need to be adjusted; click Convert to start conversion, then Download each one individually, or package them all into a ZIP for download at once.
In addition to conversion, the material also mentions three standalone tools, all of which likewise run entirely in the browser and do not upload files: the compressor is used to reduce file size without changing the format and can hit an exact target file size (which the converter cannot do); the resizer handles exact dimensions and provides ready-made presets for Instagram and YouTube, such as 1920×1080, 1080×1080, and 2560×1440, as well as dedicated pages for small sizes such as 128×128 icons, 480×640 portrait, and 640×480 landscape, plus a 1500×500 preset for Twitter banners. In addition, some features are already built directly into the converter without needing a separate tool: compress without converting (select the same format as the input and lower the quality slider), resize (open the gear settings on any file to set the maximum width, with height following automatically), image to PDF (select PDF as the output), and make a website icon (select ICO as the output to generate a browser icon from any square image).
The material also includes format explanations: an image format is a set of rules describing how an image is stored on disk, involving pixel arrangement, whether it is compressed, and accompanying information. Lossy formats such as JPG and AVIF discard details that are not easily noticed by the human eye in exchange for smaller size; lossless formats such as PNG precisely preserve every pixel.Plain, suitable for logos, screenshots, and images with sharp edges or text; WebP works for both. Another common difference is transparency: PNG, WebP, AVIF, and GIF can store transparent pixels, while JPG cannot; when converting a transparent PNG to JPG, transparent areas must be filled with a solid color. This tool uses white, while most converters default to black.
Use cases include converting images between different platforms or formats, batch processing images while ensuring privacy, compressing image file size, resizing according to platform requirements, converting photos or scans to PDF, and generating favicons, among others.
In terms of limitations, because it relies on the browser Canvas API, browsers can read many formats but can only write a limited set. Formats such as EPS, PSD, SVG, and TGA require server-side processing, and for privacy reasons this tool does not support them, so these formats cannot be converted; very large images may take a moment on slower devices. The materials do not provide data on fees, pricing, platform coverage, AI features, or specific results; this content is not currently available.
