01LOCAL ONLY
Private by design
All processing runs in your browser via WebAssembly. No file is transmitted, stored, or seen by a server. Disconnect from the internet after loading — Capcompress still works.
Open DevTools: zero network requests.
FREE IMAGE COMPRESSOR.
NO UPLOAD. NO LIMITS.
Compress JPEG, PNG, WebP and AVIF images directly in your browser — for free, in bulk, without uploading a single file. A faster, private alternative to Squoosh and TinyPNG.
Why Capcompress
COMPRESS WITHOUT UPLOADING.
BY DESIGN.
02MULTI-FILE
Batch & folders
Drop an entire folder. Capcompress reads it recursively, compresses every image in parallel across all your CPU cores, and exports a ZIP that mirrors your original folder structure.
Tested with 500+ images per session.
034 FORMATS
Convert between formats
Input JPEG, export WebP. Input PNG, export AVIF. Mix sources freely — set quality, target dimensions, and encoding effort per image or globally across the whole batch.
Lossless and lossy modes for PNG & WebP.
04ZERO FRICTION
No account. No limit.
No login, no install, no watermark, no file size cap, no daily quota. Open the page and start compressing — in Chrome, Firefox, Safari, and Edge.
No credit card. No catch. Ever.
How it works
COMPRESS IMAGES ONLINE.
THREE STEPS.
- Step 01
DROP
Drag & drop individual files or an entire folder. Capcompress scans it recursively — any depth, any structure. Accepted: JPEG, PNG, WebP, AVIF.
- Step 02
TUNE
Pick output format, quality, and target dimensions. Apply settings globally to the whole batch, or override specific images individually.
- Step 03
DOWNLOAD
Download each image individually, or export the full batch as a ZIP. The archive mirrors your original folder tree — no manual renaming needed.
Supported formats
WEBP · AVIF · JPEG · PNG.
COMPRESS OR CONVERT.
WebPRECOMMENDED
Best balance
30–80% smaller than JPEG. Transparency support. Works in all modern browsers. Lossy & lossless modes.
AVIFMAX COMPRESSION
Next-gen quality
Up to 90% smaller than JPEG. HDR & wide color gamut support. Modern browsers only. Slower to encode.
JPEGUNIVERSAL
Broadest compat
Supported on every device and platform. Great for photos. No transparency. Fastest encode speed.
PNGLOSSLESS
Pixel-perfect
No quality loss, ever. Full alpha channel. Larger files than lossy formats. Best for UI assets and graphics.
FAQ
IMAGE COMPRESSION.
YOUR QUESTIONS.
- Does Capcompress upload my images to a server?
- No. All processing runs locally in your browser via WebAssembly. No file is transmitted — not even a thumbnail. You can disconnect from the internet after loading the page and compression will still work.
- Is there a maximum file size?
- There is no hard limit. The practical ceiling depends on your device's available RAM. Most modern computers handle images up to 50–100 MB per file without issues. For large batches, Capcompress processes images in parallel to keep memory usage manageable.
- WebP or AVIF — which should I choose?
- WebP is the safer default: 30–80% smaller than JPEG, supported in all modern browsers, and fast to encode. AVIF achieves even greater compression (up to 90% vs JPEG) but encodes slower and requires browsers released after 2021. For web projects targeting broad audiences, start with WebP.
- Can I compress a PNG without losing quality?
- Yes. Select PNG as output and enable lossless mode — you get smaller files with zero visual quality loss. For the smallest lossless result, WebP lossless typically beats PNG by 20–30% on photographic content while keeping full transparency.
- Does Capcompress work on iPhone and Android?
- Yes, it works in any modern mobile browser. On iOS, use Safari or Chrome; on Android, Chrome is recommended. Mobile devices have less RAM, so very large batches may be slower — but individual images and small sets compress instantly.
- How does in-browser image compression work?
- Capcompress uses WebAssembly (Wasm) — compiled C/C++ codecs running at near-native speed inside your browser. The same encoding libraries used by desktop tools (libjpeg-turbo, libwebp, libavif) execute locally, with no server involved at any step.
Ready?
START COMPRESSING.
Drop your images at the top of the page — or click below.