Client-Side WebAssembly vs Server-Side Linux Engines for PDF Conversion
A PDF can be opened in two very different places. A WebAssembly build of a PDF library runs inside the browser tab. The bytes stay on the device, and the tab does the work. A server engine receives the file, runs a native tool, and returns text or a smaller PDF. Seoffix uses the second path for the operations that need poppler, qpdf, or Ghostscript.
What stays fast in the browser
Page preview, form filling, and a light rearrangement of pages are comfortable in WASM when the file is small and the library build includes the feature. The limit is the tab: memory, a single thread, and a feature set that may not match the desktop tool. A scanned page is a picture. WASM cannot invent a text layer that was never written.
What the Linux engines are for
pdftotext reads an existing text layer and returns the words, up to a page cap. qpdf recompresses streams and object structure without retyping the document. Ghostscript can rewrite a PDF when the file needs a deeper pass. Those programs expect a real PDF header and a file small enough to finish inside the request timeout. They do not turn a PDF into Word. The PDF suite is the place for the rest of the 26 tools, including merge, split, and compress from the browser.
Trust the processing notice
Sending a file to the server means the server has the file for the length of the job. That is not a zero-log product, and it is not a place for contracts, medical records, or credentials. Use a local application when the document must not leave the machine. Use the suite when you want the native engines and the document is safe to submit.
- Extract text when you need the words and the PDF already has a text layer.
- Compress when you need a smaller file and can accept a structural rewrite, not a promise of identical bytes.
- Keep the original until you have opened the result.
Agents can call the same extract and compress actions through seoffix_pdf_convert on the MCP server. The input is an https URL or a base64 PDF, up to 4MB.