About ConvertKit

Our Mission

ConvertKit was built to solve a fundamental problem with online image tools: they require you to upload your private files to a server before processing. We believe image resizing and compression should be instant, private, and free for everyone. That is why we built a tool that runs entirely inside your browser using the HTML5 Canvas API.

How It Works

Every resize, compression, and format conversion happens locally on your device. When you select an image, it is read into your browser’s memory and processed by JavaScript — no data is sent to any server. This architecture eliminates upload wait times, protects your privacy, and allows us to offer the service completely free without bandwidth costs.

Key Features

• 100% browser-based processing — zero server uploads
• Resize by exact pixels, percentage, or target file size
• Batch process up to 20 images at once
• Convert between PNG, JPEG, WEBP formats
• Grayscale filter and social media presets
• Download individual files or a single ZIP archive
• No registration, no accounts, no watermarks

Smart compression

ConvertKit uses adaptive compression that dynamically balances file size and visual quality based on your target parameters. Rather than applying a one-size-fits-all approach, the encoder adapts to each image’s content to deliver the best possible result.