How it works

How it works.

Three steps, and nothing ever leaves your machine.

Three steps.

No account, no upload screen, no processing queue — the whole thing runs between when you click and when the file lands in your downloads folder.

1. Pick a format

Choose from 19 real container formats — PDF, PNG, ZIP, DOCX, XLSX, CSV, MP3 and more.

2. Set the exact size

Type a size or drag the slider. The generator works out how much padding a valid file at that size needs.

3. Generate and download

The file is assembled in your browser with JavaScript — nothing is uploaded, nothing is fetched from a server.

Three processing models, not one.

ByteRivet is three product families, and they don't all work the same way. Here's exactly what happens to your file in each one — no blanket claims, just what's actually true for the tool you're using.

Test File Generator

Generates a structurally valid file at an exact byte size — for testing upload forms, size limits and automated pipelines.

  • Processing location: Your browser
  • Technology: JavaScript, in a Web Worker
  • Upload status: Never uploaded
  • Retention: Nothing to retain — the file never leaves your device

Known limitations

  • Limited by your browser's available memory, not by the tool itself
  • Very large files (500 MB+) may trigger a browser memory warning

Browser-based PDF & Image Tools

Merge, Split, Organize and Watermark PDF; Compress, Convert, Crop, Resize and Rotate Image; Images to PDF, PDF to Images and Image to Text (OCR) — twelve tools that all run locally.

  • Processing location: Your browser
  • Technology: pdf-lib and the Canvas API; Tesseract.js for OCR
  • Upload status: Never uploaded
  • Retention: Nothing to retain — the file never leaves your device

Known limitations

  • Password-protected or encrypted PDFs aren't supported by the PDF tools
  • OCR reads English text only, and only the first page of a PDF

Server-based Office Conversions

Office to PDF and PDF to Office — the two tools that need a real document engine, which only a server can run.

  • Processing location: Our server
  • Technology: LibreOffice, over HTTPS
  • Upload status: Uploaded for the duration of the conversion
  • Retention: Source file deleted immediately after conversion; result deleted after 15 minutes or as soon as you download it, whichever comes first

Known limitations

  • PDF to Excel isn't offered — a spreadsheet can't be reliably rebuilt from a PDF's layout
  • Complex layouts, unusual fonts or advanced formatting may look slightly different from the original