When not to use online image tools

“Free image tool” is not a safety rating. If the site encodes on a server, the photo is their processing input, even when the privacy page says they delete it later. Policies change. Logs exist. If you would not paste the picture into a public chat, do not drop it on a random compressor.

Do not upload these, even to a famous brand

• ID cards, passports, visas, tickets with barcodes.
• Medical screenshots, prescriptions, insurance cards.
• Kids’ photos with school badges, house numbers, or GPS still in the JPEG.
• Unreleased product shots, NDA decks, or a Slack screenshot with customer names.
• Someone else’s portrait you do not have rights to process on a third-party GPU.

For those, use a tool that never takes the bytes, or an app you already installed. StackImage is built for the first path. Strip EXIF before any share, even a local one, if the JPEG still has GPS.

Jobs a browser toolkit should not pretend to own

• RAW development and color-managed print. Use Lightroom, Capture One, or the OS Photos app.
• Layered design. That is Photopea, Photoshop, or Figma.
• Smallest-possible CDN encodes at scale. That is a build pipeline (Squoosh CLI, Sharp, ImageMagick), not a tab.
• Forensic recovery of a 64-pixel face. No upscaler has that photograph.

When a cloud tool is the honest pick

A public marketing asset you would also email in the clear can go to TinyPNG or remove.bg. You are trading privacy for a better encoder. That trade is fine when you name it. It is not fine when a “free converter” is the only tab open on a passport scan.

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