Your files. Your device.
Your privacy.
Compress, convert and optimize 27 kinds of files right here — no uploads, no cloud, no signup.
Process files locally
Drop files here — they are validated and processed inside your browser. Nothing is uploaded.
Drop files here
Files are processed locally in your browser and never uploaded.
You can select multiple files. Drag and drop or use the file picker.
Batch status
0 total0 completedBatch progress appears while jobs are active.
Job queue & results
No jobs yet. Add validated files to the queue to start processing.
Tools
Every tool below is implemented and tested — the list is generated from our capability registry, so untested formats are never advertised.
PDF compressor
Shrink oversized PDFs directly on this page. Your file is processed inside your own browser using local JavaScript and WebAssembly — it is never uploaded to any server.
JPEG compressor
Reduce the file size of JPG photos and screenshots right in your browser. The image is decoded, re-encoded and saved on your device — no upload, no queue, no watermark.
.jpg, .jpeg
PNG compressor
Make PNG files smaller in your browser with a genuinely lossless re-encode: identical pixels, identical transparency, smaller file. Optional lossy conversion to WebP is available when you want bigger savings and can accept a format change.
.png
WebP compressor
WebP usually delivers the smallest images at good visual quality. Optimize existing WebP files or convert your JPG and PNG images to WebP — all inside your browser, with no upload step.
.webp
SVG compressor
Shrink SVG files by stripping editor metadata and redundant markup. Optimization runs locally in your browser with a safety pass that removes scripts and external references before the file is ever rendered.
.svg
ZIP compressor
Bundle files into a ZIP archive, open an existing ZIP to get its contents back, or repack an archive with stronger compression. Everything happens in your browser; your files never touch a server.
.zip
How it works
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Choose a file
Your browser reads the file locally and validates its real type with extension, MIME and magic-byte checks — before anything else happens.
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Process on your device
The file's bytes are transferred into a Web Worker and processed by lazy-loaded engines. Your main browser tab stays responsive, and the bytes never reach a network.
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Download the honest result
You get the real measured size change — including "it didn't get smaller", when that's the truth. Temporary resources are released right after download.
Frequently asked questions
- Do my files get uploaded anywhere?
- No. CompressKit has no upload step: your file is read by your browser, processed by JavaScript and WebAssembly running on your device, and the result is saved straight back to your disk. The architecture contains no server that could receive file data.
- How can the tools be free with no signup?
- Because there is no processing infrastructure to pay for — your own device does the work. A backend exists only for account and payment features; it never receives file bytes, file contents or filenames.
- Which formats can CompressKit handle?
- Every tool listed on this page is implemented and tested: PDF (compress, merge, split, extract), images (JPEG, PNG, WebP, SVG), archives (ZIP, gzip, TAR, Zstandard, 7-Zip), Office documents (DOCX, XLSX, PPTX, legacy XLS conversion), CSV, developer formats (JSON, HTML, CSS, JavaScript), audio (WAV/MP3 inspection, MP3 re-encode and MP3→WAV), video (MP4/WebM convert, trim, compress and inspect), EPUB optimization and font subsetting (TTF, WOFF2). Formats that are not yet tested are deliberately not advertised.
- Does processing happen offline?
- Once the page has loaded, the tools keep working even if your connection drops, because all processing is local. For heavy WASM-based operations the engine is loaded on demand from the site, but the file data itself never travels.
- What are the size limits?
- There is no artificial limit and no account tier gating — the practical limit is your device memory. Very large files are flagged with a warning before processing so you can decide.