TinyPNG alternative that never uploads your photos

TinyPNG (and TinyJPG) earned its reputation: drop a PNG or JPEG, get a much smaller file. The encoder is the product. The file also goes to their servers. If you are shrinking a logo that is already on your homepage, that trade is easy. If you are shrinking last night’s photos, it is not.

Side by side

• Privacy: TinyPNG uploads. StackImage compresses in the tab with canvas toBlob.
• Encoder: TinyPNG’s cloud stack usually wins on the last stretch of bytes. We use the browser’s JPEG, WebP, AVIF, and lossless PNG. We do not run mozjpeg or oxipng.
• Formats: TinyPNG is famous for PNG/JPEG. StackImage also writes WebP and AVIF, and can start from HEIC via Convert.
• Batch: both can do several files. We cap at 24 files, 50 MB, 32 MP so the tab does not die.
• Account: TinyPNG’s API and higher limits are a paid product. StackImage has no account.

When to stay with TinyPNG

Stay when the asset is already public, you need their specific look at a given size, or you already pay for the TinyPNG API in a deploy script. That is a coherent product. A private tab will not clone their encoder.

When StackImage is the better TinyPNG alternative

• The photo is personal, medical-adjacent, or still has GPS in the JPEG.
• You want WebP or AVIF out, not only a smaller PNG.
• You also need resize, crop, or strip EXIF in the same sitting.
• You do not want a daily free-tier counter on a folder of screenshots.

Sources