Frequently asked questions

No. Every file is read and compressed inside your browser, on your own computer or phone. oCompress has no server that receives files, so there is nothing for us to store, view or delete. The tool only downloads its own program code from our site.

Compress one file so the engine loads, then disconnect from the internet and compress another file of the same type: it still works. You can also watch the Network tab of your browser's developer tools (F12) while compressing; no request contains your file. Details are on the how it works page.

Because the document never leaves your device, compressing a contract or a payslip here exposes it to no one beyond what already has access to your computer. As with any website, use an up-to-date browser and make sure the address bar shows ocompress.com with a secure connection.

The site uses Google Analytics and shows ads from Ezoic and Google, which use cookies. The tools report anonymous events such as the type of tool used and rough size ranges, never file names or file contents. The privacy policy lists everything.

No. The tools run in any current browser without an extension, an app or a sign-up. Open the page, drop a file, download the result. On a phone you can also choose files from your photo library or the files app.

Image and document compression work in all current versions of Chrome, Edge, Firefox, Safari and Opera. Video and most audio conversions additionally need the WebCodecs interface, which current Chromium-based browsers have, Firefox since version 130 and Safari since version 26. If your browser lacks it, the tool says so; images, documents and WAV or AIFF to MP3, FLAC or WAV keep working. Firefox cannot create AAC audio, so it uses Opus instead.

Yes, there is no limit on the number of files. Add a batch of mixed types and each file is routed to the right engine; several images are processed in parallel, videos one after another. When the batch is finished, Download all saves everything as one ZIP.

Once the page and the engine for your file type have loaded, yes. Connectivity is only needed to fetch the program code, not to process files; choosing an output format you have not used yet may first need its codec.

The files in the list are compressed again with the new setting after a short pause, so you can compare results quickly. "Reset to default" brings back the recommended preset.

It depends on how the file was created. Photos from cameras, scanned PDFs, uncompressed WAV recordings and phone videos usually shrink a lot. Files that were already compressed, such as images saved from social networks, shrink little. The tool shows the exact result for every file before you download it. If you are aiming for a specific limit, reducing the dimensions of images or the resolution of videos usually helps more than lowering the quality.

The compressed version would not have been smaller, so the tool kept your original instead of handing you a larger copy. Try stronger settings, a smaller maximum size or a different output format if you still need to save space.

With the default settings, usually not at normal viewing or listening conditions. For images, the before/after slider with zoom lets you inspect details yourself; for video and audio, the preview plays the result before you save it.

No. The files you download contain only your content, with no logo, no added text and no extra frames. That applies to every file type and every preset, at no cost.

Only if you are sure you will never need it in full quality. Lossy compression cannot be undone, so keep originals of photos, recordings and documents you may want to print, edit or archive. A good habit is to treat the compressed file as a copy for sending and the original as your master.

Images (JPG, PNG, GIF, SVG, TIFF, WebP, AVIF, BMP), video (MP4, MOV, M4V, MKV, WebM, MPEG-TS), audio (MP3, WAV, AAC, FLAC, M4A, AIFF, OGG, Opus) and documents (PDF, DOCX, XLSX, PPTX and their OpenDocument counterparts). Old DOC, XLS and PPT files can be packed into a ZIP. Each format has its own page with recommended settings, linked from the menu at the top.

Yes, because everything has to fit into the memory of one browser tab. The limits are 200 MB and 100 megapixels for images, 300 MB for PDF and Office files (120 MB on phones and tablets), 500 MB for old DOC, XLS and PPT files (200 MB on phones and tablets), and 4 GB for video and audio (1 GB on phones and tablets). The tool tells you clearly when a file is too large. Closing other tabs frees memory, and a computer copes with much bigger files than a phone.

Browsers cannot open these containers (nor WMV, FLV or MPG) and include no decoders for Windows Media audio or the old codecs found in AVI files. Convert them to MP4, WAV or MP3 with a desktop program such as VLC, HandBrake or Audacity first; the WMA and AVI pages explain how.

Most email services allow 20–25 MB per message, but attachments grow by about a third when encoded for sending. Stay around 18 MB in total for a 25 MB service. The file size limits page lists the exact numbers per service.