Which image format you want is decided by the destination, not by the picture: WebP is lighter for the web, PNG is required when you need transparency, JPEG is what you email, and some upload forms accept nothing else.
OFFiler converts between PNG, JPEG, and WebP in the browser, with a quality control and an immediate before/after size readout. Below: when to pick each format, what conversion discards, and the transparency trap that catches people out.
Choosing between the three
What each format is for
WebP reproduces the same appearance in a smaller file than JPEG, which makes it the default choice for images on a website. JPEG is the lossy photographic format that everything, everywhere, can open. PNG is lossless, and along with WebP is one of the two here that support transparency — it suits logos, icons, screenshots, and diagrams.
Quality is chosen from presets — high (90), balanced (70), small (50) — or entered directly. It applies to JPEG and WebP only, and is ignored when converting to PNG, which is lossless.
Conversion goes through a canvas
Conversion draws the image onto a canvas and re-encodes it in the target format, using the encoder the browser already ships. Nothing extra has to be downloaded, and the operation is fast.
A consequence is that what can be produced depends on the browser's own support. If a format cannot be encoded, you get an explicit error rather than a silently broken file.
What conversion costs you
Converting to JPEG turns transparency black
JPEG has no way to record transparency. Convert a transparent PNG or WebP to JPEG and the transparent regions come out filled with black — this is the reason logos and icons suddenly acquire a black background.
To keep transparency while reducing size, convert to WebP instead. If transparency is genuinely not needed, paint the background before converting.
EXIF and ICC profiles are dropped
Because the pixels pass through a canvas, EXIF (capture time, camera model, GPS) and ICC profiles do not survive. Convenient if you wanted the location gone — though if that is the actual goal, the EXIF remover states the intent more clearly.
Also note that converting lossy to lossy (JPEG → WebP, say) compresses on top of information already discarded. If you still have the original, converting from it directly preserves the most quality.
HEIC is handled elsewhere
HEIC, the iPhone default, cannot be decoded by Chrome or Firefox at all, so it is not accepted here. Run it through the dedicated HEIC converter to get JPEG or PNG first, then convert further with this tool if you need to.
Chaining around the conversion
Preparing an image for the web
To prepare an article image: resize to the display width, convert to WebP, and compress further if needed. Removing surplus pixels before changing format gets you the same appearance in a smaller file.
Specs and limits
- Output formats
- PNG, JPEG, WebP
- Size limit
- 50 MB per file
- Quality
- High 90 / balanced 70 / small 50, or a direct value
- Quality applies to
- JPEG and WebP only (ignored for lossless PNG)
- Transparency
- Kept in PNG and WebP; turns black in JPEG
- Discarded
- EXIF, ICC colour profile
- HEIC
- Not supported — use the HEIC converter
- Network
- No file upload; all processing in-browser