ImageMagick
FreeFFmpeg for images — one command, thousands of files
A command-line image processing toolset and library supporting over two hundred formats. Convert, batch-resize, crop, rotate, watermark, montage, adjust color, generate thumbnails and read or strip EXIF — any of it applied to an entire folder with one command. It is also the image engine behind a great many websites and applications.
Why we picked it
"Resize these 800 images to 1200 pixels wide and convert them to WebP" — done in a graphical program, that means clicking through each one, or finding an online batch service, possibly ad-laden, that also wants your images uploaded.
ImageMagick is the general solution, occupying the same position for images that FFmpeg holds for video. 17,162 stars, under the ImageMagick License, which permits personal, internal corporate and commercial use freely — more permissive than many assume.
Real examples (the command is magick; older versions used convert):
Batch-resize a whole folder:
magick mogrify -resize 1200x -format webp *.jpg
Convert with quality control:
magick input.png -quality 85 output.jpg
Add a text watermark:
magick in.jpg -gravity southeast -pointsize 40 -annotate +20+20 "© 2026" out.jpg
Tile several images into one:
magick montage *.jpg -tile 3x3 -geometry +5+5 grid.jpg
Strip EXIF metadata before publishing:
magick input.jpg -strip output.jpg
That last one deserves separate emphasis: phone photos routinely carry GPS coordinates, device
model and capture time, so posting one online often ships your location with it. One -strip
command clears that across a batch.
It also handles format identification, color space conversion, image comparison, PDF generation, page extraction from PDFs, and basic drawing and effects.
To be clear about:
- It is a command-line tool with no GUI. If that is unappealing, use GIMP for single images and Squoosh or Caesium for batch compression.
- Options are numerous and order-sensitive. In ImageMagick, option order changes the result (options apply to images that follow), which is the most common source of beginner confusion. Start by modifying the templates above.
mogrifyoverwrites originals. This deserves real caution — it edits in place, and a mistake destroys the source. Test on a copied folder, or use themagick input outputform to write to a new file.- It has had security vulnerabilities historically when processing maliciously crafted images. If you use it server-side on user uploads, keep it updated and configure its security policy file.
For anyone who handles images regularly, memorizing three or four commands eliminates a great deal of repetitive work.