Client-side vs server-side image compression — why I chose the browser

When I started building Tinify, the first big architectural decision was: should image compression happen on a server or in the user's browser?

Most tools (TinyPNG, Compressor.io, etc.) upload your images to a server, compress them there, and send them back. It works, and server-side processing can use more advanced algorithms.

I went the other way — 100% client-side processing using the Canvas API and browser-native encoding.

Here's why:

Privacy by architecture, not by policy. When your images never leave your device, there's no privacy policy to trust. No data breach can expose your files because they were never transmitted in the first place. For my e-commerce clients dealing with unreleased product photos, this matters.

No infrastructure costs for compression. The user's browser does the heavy lifting. This means I can offer it free without worrying about server bills scaling with usage. No need to limit file counts or sizes to control costs.

Speed. No upload wait, no download wait. Especially on larger files (Tinify handles up to 25MB), skipping the round trip makes a real difference.

The tradeoff? Browser-based compression can't match some advanced server-side algorithms. You won't get the absolute best possible compression ratio. But for the vast majority of use cases — web images, product photos, blog content — the difference is negligible, and the privacy/speed benefits win.

I'd love to hear from other builders: have you considered client-side processing for your tools? What held you back (or pushed you forward)?

Tinify launches tomorrow on Product Hunt if you want to see this approach in action.