Simple Image Compressor – Private In‑Browser JPG, PNG, WebP, HEIC Optimization

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Simple Image Compressor is a 100% client‑side image optimization tool. All compression, resizing, and format conversion happens locally in your browser—no files are uploaded, transmitted, or stored remotely. This ensures robust privacy, immediate performance, and transparent behavior suitable for personal, professional, and compliance‑sensitive workflows.

Core Features

Batch compression of up to 50 images in one session
Format conversion between JPG, PNG, WebP; automatic HEIC → JPEG
Quality presets (Maximum, High, Balanced, Aggressive) plus fine‑grained slider control
Optional target size (KB) iterative loop for approximate size goals
Resize by maximum width/height while preserving aspect ratio
Visual before/after comparison slider to assess fidelity
Per‑image download and bulk ZIP export preserving filenames
Local settings persistence (quality, format, dimensions, compare toggle)
Offline‑capable via Progressive Web App manifest + Service Worker
Responsive layout and accessibility‑aware interactive elements

Supported Formats & Behavior

Format	Import	Compression	Conversion Targets	Key Notes
JPEG / JPG	Yes	Lossy re‑encode (quality scaling)	PNG, WebP	Ideal for photographic content
PNG	Yes	Re‑encode	JPG, WebP	Transparency retained (PNG/WebP)
WebP	Yes	Lossy / Lossless	JPG, PNG	High efficiency modern codec
HEIC / HEIF	Yes	Converted	JPEG	Browser conversion via in‑memory decode

Step‑By‑Step Usage

Drag or select up to 50 images (large images warn at >20MB; blocked at >50MB)
Choose a quality preset or adjust the slider for custom balance
Optionally set resize constraints and/or a target size (KB)
Start compression and monitor per‑file progress indicators
Use the comparison slider to inspect visual fidelity vs. size savings
Download single optimized images or export a ZIP bundle
Clear images (settings persist) to begin a new batch

Privacy & Data Handling

All operations (decoding, resizing, recompression, format conversion) leverage local browser APIs (Canvas, Blob, WebCodecs where supported, in‑memory transformation). No image bytes leave your machine. We do not embed third‑party analytics in the compression workflow and do not retain any file data. Temporary object URLs are revoked to free memory after clearing images.

FAQ

Are my images uploaded? No. Processing is fully local—suitable for confidential assets.

Will compression ruin quality? Presets aim for perceptual retention. Adjust quality upward if artifacts appear.

Why is HEIC converted to JPEG? Wide compatibility and consistent decoding pipeline; JPEG quality adjustable.

Can I retain transparency? Yes—use PNG or WebP outputs; JPEG discards alpha.

Is there a size limit? Practical soft limit at 50MB per file to avoid memory strain.

Does it work offline? After first load, assets are cached (PWA) enabling offline usage.

How is target size approximated? Iterative downscaling of quality until near threshold; may vary by image complexity.

What browsers are supported? Latest Chrome, Firefox, Safari, Edge. Older versions may skip HEIC conversion.

Why do very small images not shrink much? Already optimal or dominated by format overhead.

Can I reset settings? Clear images retains settings to streamline batches; full reset planned.

Troubleshooting

Stall on huge file: Resize first; reduce dimensions to accelerate encoding.
HEIC fails: Update to a modern browser; fall back to manual conversion utilities.
Output too soft: Raise quality slider or switch preset to High/Maximum.
Need smaller size: Lower quality gradually or specify a target size (KB).
ZIP missing file: Ensure compression finished; wait for completion indicators.

Example Savings

Image Type	Original	Compressed	% Saved	Preset
Portrait (JPEG)	2.9MB	720KB	75%	Balanced
UI Screenshot (PNG→WebP)	1.4MB	410KB	71%	High
Phone HEIC	2.2MB	1.05MB	52%	Aggressive

Note: Results vary based on texture complexity, gradients, and noise.

Enable JavaScript in your browser settings to activate the interactive compression interface and begin optimizing images locally.