How in-browser processing works

The usual way, and our way

Most online converters work like this: you upload your file to their server, the server converts it, and you download the result. Your contract, ID scan, or family photo makes a round trip through someone else’s computer, subject to their retention policy and security.

Convertly Tools works differently. Modern browsers contain remarkably capable image and document machinery, and our tools run entirely on it. The page you load contains all the code needed to do the conversion; your file is opened, processed, and re-encoded in your browser’s memory, on your device. There is no upload step. Not a fast one, not an encrypted one, none.

What each tool uses

Every file tool runs on one of these in-browser technologies:

• PNG, JPG, WebP, BMP, GIF & AVIF converters: Your browser’s built-in image engine (Canvas API)
• HEIC to JPG: A HEIC decoder compiled to WebAssembly, shipped inside this site’s own code
• TIFF to JPG: A TIFF decoder written in JavaScript (utif), bundled with the site, because browsers can’t read TIFF natively
• Image Compressor, Resizer, Rotator & Cropper: Canvas API re-encoding on your device
• JPG/PNG to PDF, Merge, Split: An in-browser PDF library (pdf-lib) running in the page
• PDF to JPG, PDF to PNG, PDF to Text & PDF Compressor: The same PDF renderer your browser uses (pdf.js), loaded from this site
• JSON Formatter: Your browser’s own JSON parser. No file is involved and nothing is sent anywhere
• Background Remover & Background Blur: One open-source AI model (MODNet, Apache 2.0) run in your browser by ONNX Runtime, on your graphics chip via WebGPU where available, otherwise on the CPU. Downloaded once and cached; your photo is never uploaded
• Image Upscaler: Swin2SR lightweight (Apache 2.0) via ONNX Runtime on WebGPU, processing the image in 256-pixel tiles. Requires WebGPU. On the CPU a single tile takes ~18 s and would freeze the page, so the tool declines instead
• Privacy Blur: UltraFace (MIT), a 1.2 MB face detector run by ONNX Runtime on the CPU in about 35 ms. Blurring and pixelation are plain Canvas API. Chosen over MediaPipe, which reports usage to Google with no opt-out
• “Download all” ZIPs: Assembled in your browser’s memory (client-zip)

None of these make network requests with your file’s contents. The HEIC decoder deserves a special note: decoding Apple’s format needs real codec work, which we ship as WebAssembly inside the site’s own JavaScript, downloaded once as ordinary site code, then run locally.

The same holds for text you paste rather than upload. The JSON Formatter parses what you paste with the browser’s own JSON.parse, never eval, so pasted config, tokens, or API responses are read in the page and never transmitted.

Verify it yourself in two minutes

You don’t need to trust this page. Your browser can prove it:

• Open any tool, for example PNG to JPG.
• Open your browser’s developer tools (F12 or right-click → Inspect) and switch to the Network tab.
• Drop in a file and convert it.
• Watch the request list: you’ll see the page load its own scripts, and no request carrying your file anywhere. The conversion happens even if you disconnect from the internet after the page loads.

The one exception: the SKILL.md Generator

The SKILL.md Generator drafts skill files for Claude, and drafting needs a language model, which does not fit in a browser tab. When you press Generate, the text you typed into its form is posted to a small function on our server and forwarded to Anthropic’s API, which writes the draft and sends it back. No file is involved, only the description you typed. We do not store it, log its contents, or send it to analytics; Anthropic handles it under its own API data policy. The page says all of this above the button, and it is the only tool on the site that sends anything you enter off your device.

What does leave your device

Honesty requires the full picture. Like most websites, we load the site’s own code and fonts from our server, and, only if you accept the cookie banner, Google Analytics records page-level usage (which tools are popular, never file contents). If ads are shown, Google AdSense loads its script. None of these ever receive your files or anything derived from them. Details in our Privacy Policy.

What this means in practice

• Confidential documents stay confidential: contracts, statements, and IDs are processed without ever being transmitted.
• There’s no server queue, so conversion starts instantly.
• There’s nothing for us to store, leak, or delete. We never had your file.
• Large files are limited only by your device’s memory, not by an upload cap.

Any tool that sends your input to a server says so on its page before you use it. Today that is one tool, described above. That commitment is in our Privacy Policy.