Drop Photoshop PSD or PSB files. The flattened picture Photoshop stores inside each one is read by this site's own PSD reader and written as JPEG or PNG — no Photoshop needed, nothing uploaded.
What is read: the stored composite
When Photoshop saves with “Maximize compatibility” (its default), it writes a flattened copy of the whole image next to the layers, so other programs can show the picture without understanding layers. This page reads that composite — RGB, greyscale, indexed, bitmap, duotone or CMYK, 8 or 16 bits per channel, raw or RLE-compressed — and converts it.
Layers, effects and adjustment layers are never redrawn here. If the file was saved without a composite, the page says so and tells you how to fix it, instead of handing back a blank picture.
JPEG or PNG
PNG keeps every pixel and the transparency of a PSD saved with a transparent background. JPEG is far smaller for photographs and is searched to the lowest quality that still measures visually identical (0.990 at 512 px); transparent areas need a background colour first. 16-bit files are reduced to 8 bits per channel and CMYK files are converted to RGB without a colour profile, which the page notes.