User guide — Compress images free with Flowfiles

Step 1 — Drop your images

Drag one or more image files directly onto the drop zone, or click it to open the file picker. Flowfiles accepts JPEG, PNG, WebP, GIF and BMP files. There is no size limit enforced by the tool — the only limit is your device's available memory.

• You can add files one by one or all at once.
• Each file appears as a card with its original size and dimensions.
• You can remove individual files before processing.

Step 2 — Choose quality mode or target size mode

Flowfiles offers two ways to control output file size.

Quality mode lets you set a compression level from 0 (smallest, most artifacts) to 100 (largest, no visible loss). A value of 75–85 is a good starting point for most photos. Lower values compress more aggressively.

Target size mode lets you type a maximum file size in KB. The tool finds the right quality level automatically. Use this when a platform imposes a strict file size limit — for example 100 KB for a passport photo portal or 50 KB for an online application form.

Step 3 — Resize by width (optional)

Enter a maximum width in pixels to resize the image before compressing it. The height adjusts automatically to preserve the original aspect ratio — no distortion. Resizing and compressing together produces the smallest possible output file.

• 600 px — typical email content width.
• 1200 px — blog posts and article illustrations.
• 1920 px — full-width desktop hero images.
• Leave the field empty to keep the original dimensions.

Step 4 — Choose the output format

The format you pick affects both file size and compatibility.

• JPEG — the safest choice. Compatible with every platform, email client and device. Best for photographs.
• WebP — typically 25–35% smaller than JPEG at the same quality. Supported by all modern browsers. Avoid for Outlook and some legacy platforms.
• PNG — lossless compression with transparency support. Best for logos, screenshots and images with text. File sizes are larger than JPEG for photos.

Step 5 — Batch download as ZIP

After compression, download each file individually with its button, or click the ZIP button to get all files packed in a single archive. The ZIP is assembled in your browser — nothing is sent to a server.

• Filenames keep the original name with the new format extension.
• The ZIP download is available as soon as at least two files are ready.

Before/after comparison

Each result card shows the original file size and the compressed file size side by side. You can see the reduction in KB and as a percentage. Open the preview to compare visual quality before downloading.

If the compressed file is larger than the original — which can happen with already-optimized WebP files — Flowfiles will warn you so you can adjust quality or switch format.

Frequently asked questions