Let me check the API routes to understand why the downloaded files aren't opening:

I see the problem. The API routes are just returning the original file buffer with a different content-type header, but not actually converting the file format. The file content is still the original format (PDF or PPT), just renamed. I need to implement actual conversion using libraries. Let me fix this by using pptxgenjs to create proper PPTX files and pdf-lib for PDF generation:

I've fixed both API routes. Now they generate actual valid file formats:

PDF to PPT: Uses pdf-lib to read the PDF pages and pptxgenjs to create a real PowerPoint file with one slide per PDF page, containing slide numbers and page dimension info.

PPT to PDF: Uses jszip to extract text content from PPTX files (which are ZIP archives) and pdf-lib to create a proper PDF with slides rendered as pages, including headers, titles, bullet points, and footers.

The downloaded files will now open correctly in their respective applications (PowerPoint for .pptx and any PDF reader for .pdf).

This is a comprehensive request to add many PDF tools. Based on the screenshots from PDF24, I can see the following categories:

1. Frequently Used: Merge, Split, Compress, Edit, Sign PDF, etc.
2. Convert to PDF: Word, PowerPoint, Excel, Images, JPG, PNG, WEBP, HEIC, SVG, TIFF, DOCX, Text, etc.
3. Convert from PDF: PDF to Word, PowerPoint, Excel, Images, JPG, PNG, Text, HTML, etc.
4. Convert Images: HEIC to JPG/PNG, WEBP to JPG/PNG
5. More Tools: Rotate, Watermark, OCR, Split, etc.

This is a large project. Let me set up a todo list and build this systematically with working tools: