The Technical Side of Paste to Download

PasteSave pairs a small server that delivers pages with tools that do all of their file processing in your browser.

How It Works

Every tool follows the same four-step pattern:

  1. Paste or choose local files.
  2. Browser APIs decode and inspect them.
  3. Canvas, WebAssembly, ONNX Runtime Web or PDF libraries process them on your device, depending on the tool.
  4. The browser assembles the result and saves it locally.

Throughout this flow the content of your files stays in the browser; it is not uploaded to our servers for processing.

Our tech stack includes:

  • Vanilla JavaScript with Alpine.js for the UI
  • Canvas API and WebAssembly codecs for image work
  • ONNX Runtime Web models for the AI tools (background removal, upscaling, inpainting)
  • pdf-lib and JSZip for the PDF and packaging tools
  • Tailwind CSS for styling; several libraries and models load from CDNs on first use

Security & Privacy

We highly value user security and privacy. The project design follows these principles:

  • Local file processing - The files you select are processed in your browser and are not uploaded for processing
  • Site storage is separate from your files - The site stores small preferences (like theme and language) in your browser; your image and PDF content is not written to our servers
  • Dependencies loaded as needed - Third-party libraries and AI models load from CDNs when a tool needs them; they run in your browser and your files are not uploaded to them

Technical Limitations

Since we use pure frontend technology, the project has some technical limitations:

  • Runs in modern browsers; some tools need newer APIs (WebAssembly, and WebGPU when available)
  • Large files and big batches are limited by your device's memory
  • Each tool has explicit file-size or pixel caps; unusual format variants may fail to decode
  • Several libraries and AI models download over the network on first use (up to ~40 MB)
  • AI results are best-effort — edges, fine textures and complex scenes are not always perfect

What the tools can do today

All 14 tools are live, free, and browser-local:

The first version of the core paste tool is open source on GitHub. Everything the tools do runs in your browser, so you can inspect the network activity and the delivered JavaScript at any time. If you have any questions or suggestions about the technical implementation, please contact us at: [email protected]