About Sigify's Image Format Converter
Sigify's Image Format Converter is a 100% browser-based tool that re-encodes images between JPG, PNG, WebP and BMP using the HTML5 Canvas API. The transformation is real — every output is freshly encoded to the selected format, never a file-extension rename.
For JPG output you can supply a background colour to fill the alpha channel (because JPG cannot store transparency). PNG and WebP keep alpha. BMP is uncompressed and is supported for Windows-legacy compatibility.
Real Re-Encode
Output frames are encoded from the original pixels, not just renamed.
Quality Slider
10-100 % for JPG / WebP. PNG and BMP are lossless / uncompressed so the slider is locked.
Resize While Converting
Percentage or pixel width × height, with aspect-ratio lock and upscaling protection.
Transparency Safe
PNG and WebP keep transparency. JPG uses the chosen background colour.
Batch ZIP
Convert dozens of images in one click and grab them all as a single ZIP archive.
Privacy-First
Client-side only. No uploads, no telemetry, no login.
When to Convert JPG / PNG / WebP
JPG ↔ PNG: PNG excels at UI screenshots, line art, and graphics with transparency. JPG is best for continuous-tone photos and tiny web payloads. WebP is the modern replacement for both — typically ~30 % smaller than JPG at the same perceived quality, with full transparency support. BMP is uncompressed and useful mainly for archival or compatibility with legacy Windows software.
Recommended Settings
For web / blog: JPG quality 80-85% keeps most users happy. For social media: JPG 90 % for Facebook, PNG for Instagram stickers. For retina displays: WebP quality 85% saves bandwidth.