What OnlyJPG Does

OnlyJPG converts many image and document formats into standard JPEGs in your browser. Nothing uploads to a server. You get broadly compatible JPG files that open in almost any app and device.

Quality and size controls are built in. We use Google’s Jpegli encoder with sensible defaults. You can adjust quality, chroma subsampling, progressive mode, color model (XYB or YCbCr), and choose what metadata to keep.

Private by design. Compression and rasterization happen on your device. Usage stats are optional and anonymous.

Today’s Impact

How We Estimate Carbon

Smaller files mean every future download uses less energy. We estimate potential reduction using the Sustainable Web Design model: data-transfer energy × grid carbon intensity.

• Energy intensity (SWDM v3): 0.81 kWh per GB transferred.
• Global default grid intensity: 442 g CO₂e per kWh.

This reflects data-transfer only and excludes the one-time CPU cost to compress on your device.

Your Privacy & Our Stats

Your images stay on your device. All compression happens locally in your browser. We don’t upload or store files.

To show impact, we collect anonymous counts (image totals, bandwidth saved). To prevent spam, IPs are used for short-lived rate-limits and are never stored with stats.

You’re in control. Opt out right here—or use the settings panel (gear above) any time:

Estimated Downstream Savings

The stats above show direct savings from avoiding uploads and downloads. This panel estimates the additional, collective impact of sharing smaller files. We assume 10% of images are shared and each is downloaded an extra 3 times.

Thanks Everyone!

OnlyJPG is built on the shoulders of giants. We’re grateful to the open-source community and service providers who make this tool possible.

Jpegli

The core high-fidelity JPEG encoding library from Google that powers the app's compression engine.

Emscripten

The compiler toolchain used to compile Jpegli's C++ codebase into high-performance WebAssembly.

PDF.js

Enables client-side rasterization of PDF files into images for processing.

@resvg/resvg-wasm

A high-performance WebAssembly port of the resvg library, used for accurately rasterizing SVG images.

libheif-js

A WebAssembly library that enables the browser to decode HEIC/HEIF images.

geotiff.js

A robust library for parsing TIFF files, used as a primary decoder for multi-page TIFF images.

UTIF.js

A compact and fast JavaScript library for decoding various types of TIFF images, used as a reliable fallback.

@jsquash/avif

Part of the jSquash project, providing a fast, WebAssembly-based decoder for AVIF images.

Three.js

The 3D library used to render the interactive globe in our statistics header.

Material Web

Provides the high-quality, themeable user interface components like sliders, switches, and cards.

fflate

An extremely fast, lightweight JavaScript library for creating ZIP archives for downloads.

ExifReader

A JavaScript library used to parse EXIF, ICC, and XMP metadata from source images.

es-module-shims

A polyfill that provides support for JavaScript import maps in all modern browsers, simplifying module loading.

Bun

The fast JavaScript runtime powering our anonymous statistics backend.

SQLite

The embedded database used by our statistics server for fast, reliable data storage.

Nginx

The high-performance web server that serves our static application and API proxy.

Cloudflare

Provides the edge cache, proxy, and security services for the application and its stats API.

jsDelivr, UNPKG, & esm.sh

The trio of CDNs used for resilient, multi-region delivery of our third-party modules and decoders.

Google Fonts

The service used to deliver the Atkinson Hyperlegible and Roboto typefaces.

Solar System Scope

Provides the high-resolution Earth textures for the globe visualization, licensed under CC BY 4.0.

Live Cloud Maps

The source for the cloud and specular map overlays, derived from EUMETSAT data and available under CC0.

Terms of Service

OnlyJPG is a free tool provided “as-is,” without warranties. Always keep backups of your originals.

Use it for good. Don’t use it for illegal, malicious, or abusive purposes.

We are not liable for issues or data loss arising from its use.

Write Us!

Because we don't know what we don't know!

hello [at] onlyjpg [dot] com