Is the conversion lossy?

JPEG is a lossy format, so a small amount of quality is lost. Quality 90 is visually indistinguishable for most photos.

What happens to transparency?

JPEG does not support transparency. Transparent pixels are filled with the chosen background colour (default white).

No. The page runs canvas re-encoding entirely in your browser.

Pick one or more .webp files.
Adjust the JPEG quality slider — 90 is a safe default; 75 produces visibly smaller files.
Optionally choose a background colour for transparent pixels.
Press Convert to JPG, then download each result.

Sending to anyone: JPEG is supported everywhere; WebP still trips up some apps.
Printing: photo labs almost always require JPEG.
Email attachments: reduce size compared with lossless WebP/PNG.

What quality setting should I pick?

90 keeps photos visually identical. 75 is a common web-quality setting. Below 60, artefacts get visible.

Why does the background colour matter?

JPEG cannot store transparency, so any transparent pixels are flattened against this colour during conversion.

Does it run on mobile?

Yes — Safari on iOS 16+, Chrome and Firefox on Android all support WebP decoding and JPEG encoding via the canvas API.