About the Image Format Detector
Image Format Detector gives you professional results in seconds, straight from your browser. There is nothing to install, no account to create, and no file-size games — and since processing is done locally, your documents stay on your computer.
Identify the true format, dimensions and size of any image file. Whether you are on a work laptop where you cannot install software, a Chromebook, or your phone, the tool behaves the same: open the page, add your file, download the result.
Key Features
100% private processing
Files are processed with JavaScript inside your browser. Nothing is uploaded, so nothing can be intercepted, stored or leaked.
Quality you control
Adjustable settings and a live preview let you check the result before downloading — no blind conversions.
Completely free, no limits
No trial periods, no watermarks, no daily quotas and no account requirement — every feature is free for personal and commercial use.
Works on any device
Runs in Chrome, Firefox, Edge and Safari on Windows, macOS, Linux, Android and iOS. If it has a modern browser, it works.
Instant results
Because there is no upload or download queue, processing starts the moment you add a file and usually finishes in seconds.
Batch friendly
Where the task allows it, you can drop several files at once and download the results together as a ZIP.
How to Use the Image Format Detector — Step by Step
Add your file
Click the upload area or drag and drop your file directly onto it. On phones you can pick from your gallery or camera.
Choose your settings
Adjust the options that appear — quality, size, format or layout depending on the tool. Sensible defaults are pre-selected, so you can also skip straight ahead.
Run the tool
Press the action button and watch the progress bar. Everything happens locally, so speed depends only on your device — not on a server queue.
Download the result
Preview the output where available, then click download. Multiple output files are automatically bundled into a convenient ZIP archive.
Why Use an Online Image Format Detector Tool?
Under the hood, the tool uses the HTML5 Canvas API — the same hardware-accelerated graphics engine browsers use for games and visualizations. Your image is decoded into raw pixels on your device, transformed there, and re-encoded to your chosen format, with no server round-trip at any point.
Choosing the right tool usually means trading off cost, convenience and privacy. Desktop suites are powerful but expensive and heavy; upload-based sites are convenient but ask you to trust them with your files. Local in-browser processing is the third way — the convenience of a website with the privacy of offline software, at no cost.
Onnax Tools vs. Traditional Software
| Aspect | Onnax Tools (this tool) | Desktop software / upload services |
|---|---|---|
| Price | Free, unlimited | Often $10–25/month subscription |
| Installation | None — works in any browser | Download and install required |
| File privacy | Files never leave your device | Files uploaded to company servers* |
| Registration | Not required | Account usually required |
| Watermarks | Never | Common on free tiers |
| Works on phones | Yes, fully responsive | Often desktop-only |
*Applies to upload-based online services; desktop software keeps files local but must be purchased and installed.
Common Use Cases
- Bloggers and site owners optimizing images for faster page loads and better SEO
- Social media managers producing correctly sized visuals for every platform
- Designers doing quick edits without opening heavyweight software
- Students and teachers preparing images for presentations and printed materials
- Anyone freeing up phone storage by shrinking photo collections
- Online sellers preparing product photos that meet marketplace size and format rules
📖 Want the full walkthrough? Read our detailed guide: How to Detect an image's true format in Your Browser — Free, Private & Fast