I Built 21 Free PDF Tools That Never Upload Your Files - on a $0 Stack

Description and use

The author built 21 free PDF tools that never upload files, running entirely client‑side with a $0 hosting stack, addressing privacy concerns.

Problem

Free PDF tools typically require uploading files to a server, raising privacy concerns and uncertainty about data retention.

Outcome

The project demonstrates that privacy‑first PDF tools can be built entirely client‑side with zero hosting cost, challenging the industry norm of server uploads.

Workflow

• 1. User selects a PDF via the File API.
• 2. The file is read as an ArrayBuffer.
• 3. Web Workers process the PDF with pdf-lib or pdf.js for manipulation.
• 4. For OCR, Tesseract.js runs in a Web Worker to extract text.
• 5. Results are displayed and downloadable without any server interaction.

Evidence

upload your file, wait, download it back, hope nobody kept a copy.

Source

every tool runs client‑side in the browser.

Source

Next.js on Vercel's free tier

Source

Supabase free tier (auth + a tiny bit of backend)

Source

pdf-lib and pdf.js for in-browser PDF manipulation

Source

Tesseract.js for client-side OCR

Source

The business model is "no business model" (for a year)

Source

I underestimated how much people care about this.

Source