File Size Reducer

Why this is the best free file size reducer

A file size reducer (or file compressor) shrinks the number of bytes a file takes up while keeping it usable and looking as close to the original as possible. It does this by removing redundancy, discarding detail you cannot perceive, stripping needless metadata, and - where it helps - re-encoding to a more efficient modern format.

This tool reduces images, PDFs, Office documents, audio, video and archives entirely in your browser. You drop in files, it analyses them and estimates the savings, you choose a compression level or a target size, you preview the result, and you download the optimized files. Image, PDF, document and archive compression run with native browser APIs; audio and video reuse a real in-browser ffmpeg engine. Nothing is ever uploaded.

• Compress images, PDFs, documents, audio, video and archives
• Lossless, lossy, smart and AI-assisted compression
• Convert to efficient formats (WebP, AVIF, H.265, Opus)
• Target a specific size (1MB, 500KB) or percentage
• Before/after preview with quality and savings scores
• 100% private - everything runs on your device

Large files are slow and expensive. They take longer to upload and download, eat cloud-storage quotas, bounce off email attachment limits, and drag down website performance and SEO. Compressing them fixes all of that at once, usually with no visible loss of quality.

For the web specifically, image and video weight is the single biggest factor in page speed. Serving a 200KB WebP instead of a 2MB PNG can take seconds off load time, improve Core Web Vitals (LCP), and lift search rankings - while looking identical to visitors.

• Faster uploads and downloads
• Lower cloud-storage and bandwidth costs
• Better SEO and Core Web Vitals
• Faster websites and apps
• Easier email and chat sharing
• More room on phones, drives and backups

How to reduce file size in 4 steps

Compression methods explained

Six modes cover every need. Ultra Fast favours speed with light compression. Balanced is the recommended all-rounder, giving the best quality-to-size ratio. Maximum Compression produces the smallest possible file, leaning on modern formats and lower quality. Quality First preserves the most detail. AI Optimize automatically chooses the best format and settings per file. Custom hands you every control - quality sliders, format, resize, codec, bitrate, DPI and more.

On top of the modes, you can set a target file size or a reduce-by percentage. For images the tool binary-searches the quality to land just under your target; for audio and video it picks an appropriate bitrate.

The image engine decodes your picture, optionally resizes it, and re-encodes it through the browser canvas with full control over format and quality. Re-encoding inherently strips EXIF, GPS and other metadata, which both shrinks the file and protects your privacy. You can output JPEG, PNG, WebP or AVIF, or keep the original format.

The biggest wins usually come from two moves: resizing an image to the dimensions it is actually displayed at, and converting to a modern format. WebP is typically 25-35% smaller than JPEG; AVIF can be 50% smaller again. Smart mode tries several encoders and keeps the smallest, so you never have to guess.

• JPEG, PNG, WebP and AVIF output
• Resize, scale or fit to maximum dimensions
• Automatic EXIF / GPS / metadata removal
• Transparency flattening when converting to JPEG
• Smart mode: smallest of multiple encoders
• Target-size mode via quality binary search

PDFs bloat for two reasons: heavy embedded images and accumulated metadata/objects. The Light strategy re-saves the PDF with object streams and strips metadata, keeping text fully selectable - safe, fast and good for over-saved documents.

The Rasterize strategy is for image-heavy or scanned PDFs: each page is rendered at a target DPI, re-encoded as JPEG (optionally grayscale), and reassembled into a new PDF. This can cut size by 70-90% on scans. The trade-off is that pages become images, so text is no longer selectable - ideal when the PDF is essentially photos to begin with.

• Light: object-stream re-save + metadata cleanup (keeps text)
• Rasterize: downsample pages to a target DPI (huge savings on scans)
• Adjustable JPEG quality and DPI
• Optional grayscale for text-only scans
• Runs entirely in your browser via pdf.js + pdf-lib

Video compression runs on a real in-browser ffmpeg (WebAssembly) engine. You can re-encode to H.264 for universal playback, H.265/HEVC for ~50% smaller files at the same quality, or VP9 for the open web. Lower the resolution (1080p to 720p halves the pixels), reduce the frame rate, cap the bitrate, or remove the audio track entirely.

Quality is controlled with CRF - a constant-quality target where higher numbers mean smaller files. CRF 23 is visually lossless, 28 is a strong default, and 32 squeezes hard. Faststart is applied so MP4s stream and start playing immediately on the web.

• H.264, H.265/HEVC and VP9 encoders
• Resolution, frame-rate and bitrate control
• CRF quality targeting
• Audio bitrate control or remove audio
• Web faststart (moov atom moved to the front)

Audio is compressed with the same in-browser ffmpeg engine. Lossless WAV and FLAC files are huge; encoding them to MP3, AAC or Opus typically shrinks them by 80-90% with excellent quality. For existing lossy files you can simply lower the bitrate or convert to the more efficient Opus codec.

Further savings come from reducing the sample rate (48kHz to 44.1kHz or lower for voice) and converting stereo to mono for podcasts and voice recordings, where stereo adds size with no benefit.

• MP3, AAC, Opus and OGG output
• Bitrate reduction (down to 48 kbps)
• Sample-rate reduction
• Stereo to mono conversion
• Metadata removal

DOCX, PPTX and XLSX files are really ZIP packages, and most of their weight is embedded images. The document optimizer unzips the package, recompresses those images, re-zips at maximum compression and can strip metadata - often cutting a slide deck or report in half without touching the text or layout.

For ZIP and TAR archives, the optimizer re-compresses at maximum DEFLATE, recompresses any images inside, and can remove byte-identical duplicate files. Already-compressed archives (7z, RAR) and media give little extra, and the tool tells you when that is the case rather than pretending.

• Recompress images inside DOCX / PPTX / XLSX
• Re-zip ZIP / TAR at maximum DEFLATE
• Remove duplicate files from archives
• Strip document metadata and hidden data
• Honest about formats that cannot be improved in-browser

AI Optimize analyses each file and chooses the best strategy automatically - the most efficient format, an appropriate quality, and whether to resize. For an image batch it might convert PNGs to WebP, push photos to AVIF, and leave already-tiny files alone. The goal is maximum savings at high quality with zero manual tuning.

It also powers format recommendations you will see in the analysis panel: PNG to WebP, JPG to AVIF, MP4 to H.265, WAV to AAC. These are based on the real file you uploaded, not generic advice, and you always preview the outcome before committing.

Use cases

Supported file types

Compress images, documents, audio, video and archives - all in your browser.

Recommended settings by scenario

Compression is parallelised across the queue, metadata reads only the bytes it needs, and the preview virtualises long lists. Image, PDF, document and archive work happens on your CPU with no upload, so throughput scales with your machine instead of a server queue.

Very large videos are handled by the WebAssembly ffmpeg engine, which streams frames rather than loading everything into memory. For the biggest enterprise workloads, the optional API offers server-side and async processing with webhooks; the in-browser tool is ideal for everyday files up to several gigabytes depending on your device.

This compressor is private by design. Files are read with the browser File API and processed in memory - images, PDFs and documents on the main thread, audio and video in a WebAssembly worker. Nothing is uploaded, so there is no server copy to leak, cache or delete. Close the tab and everything is gone.

That makes it safe for confidential material: client documents, financial PDFs, unreleased media and personal photos. Re-encoding images also removes EXIF and GPS data, so you can compress and de-identify in one step. There are no accounts, watermarks or hidden processing.

File Compression API & enterprise

For automated pipelines, the same optimization is available as a REST API with image, PDF, video and audio compression endpoints, batch processing, async jobs, webhooks, API keys, team accounts and usage analytics. Use it to optimise uploads at ingest, shrink assets in a DAM, or run scheduled bulk storage cleanups. Pricing scales from a free tier to enterprise with SLAs and a storage-cost calculator.

Frequently Asked Questions