Batch Image Processor — Free, Fast & Private
Cloud-based bulk image processors charge per image, store your photos, and hit you with monthly quotas. MiniPx's batch processor runs entirely in your browser — drop a folder, process every image, download a ZIP. Your photos never touch a server. The Pro tier removes the 5-file batch cap; Free handles up to 5 images per batch.
Combined with other Pro features, a single batch can do remarkable amounts: 50 input images × 4 responsive sizes × 4 formats = 800 output files in one pass, packaged as a ZIP with srcset-named filenames, every output watermarked, all processed in your browser. Memory is the only ceiling — modern laptops handle 100+ images comfortably.
Use cases: photographers preparing portfolio drops, e-commerce stores re-encoding their entire product catalog to AVIF for performance, design teams generating responsive variants for a marketing campaign, developers preparing assets for a website launch.
For the workflow specific to bulk compression (not Pro-gated), see the existing Bulk Image Compressor landing page. See pricing for the Pro plan that removes the 5-file cap.
Batch convert: what actually makes it fast
Batch conversion is not one operation repeated — it is a pipeline, and the slow step is rarely the encoding. On any upload-based service the bottleneck is the network: 200 photos at 8 MB is 1.6 GB up and a few hundred megabytes back, at which point a large batch becomes an exercise in not losing your connection.
Processing locally removes that entirely. Files are read from disk, decoded, re-encoded and written back, so throughput depends on your processor rather than your upload speed — and a mid-range laptop encodes a JPEG in a few milliseconds. Compression runs in a Web Worker, so the interface stays responsive while a long batch works through.
The practical advice for large batches: convert to a single output format rather than mixing, since one encoder path is faster than several; set the width once for the whole set rather than per file; and keep an eye on memory, because a very large batch of very large images is the one thing that will make a browser struggle. On the free tier a batch is 5 files; Pro removes the cap. Related: batching a 30-60 image property shoot.
For the workflow around large jobs rather than the mechanics, see the bulk image compression guide.